diff --git a/crates/js-component-bindgen-component/src/lib.rs b/crates/js-component-bindgen-component/src/lib.rs
index 9535ad2e8..fd8800b7b 100644
--- a/crates/js-component-bindgen-component/src/lib.rs
+++ b/crates/js-component-bindgen-component/src/lib.rs
@@ -53,6 +53,17 @@ impl From<BindingsMode> for js_component_bindgen::BindingsMode {
     }
 }
 
+impl From<AsyncMode> for js_component_bindgen::AsyncMode {
+    fn from(value: AsyncMode) -> Self {
+        match value {
+            AsyncMode::Sync => js_component_bindgen::AsyncMode::Sync,
+            AsyncMode::Jspi(AsyncImportsExports { imports, exports }) => {
+                js_component_bindgen::AsyncMode::JavaScriptPromiseIntegration { imports, exports }
+            }
+        }
+    }
+}
+
 struct JsComponentBindgenComponent;
 
 export!(JsComponentBindgenComponent);
@@ -76,6 +87,7 @@ impl Guest for JsComponentBindgenComponent {
             multi_memory: options.multi_memory.unwrap_or(false),
             import_bindings: options.import_bindings.map(Into::into),
             guest: options.guest.unwrap_or(false),
+            async_mode: options.async_mode.map(Into::into),
         };
 
         let js_component_bindgen::Transpiled {
@@ -162,6 +174,7 @@ impl Guest for JsComponentBindgenComponent {
             multi_memory: false,
             import_bindings: None,
             guest: opts.guest.unwrap_or(false),
+            async_mode: opts.async_mode.map(Into::into),
         };
 
         let files = generate_types(name, resolve, world, opts).map_err(|e| e.to_string())?;
diff --git a/crates/js-component-bindgen-component/wit/js-component-bindgen.wit b/crates/js-component-bindgen-component/wit/js-component-bindgen.wit
index 13e36eb32..ef8acb17a 100644
--- a/crates/js-component-bindgen-component/wit/js-component-bindgen.wit
+++ b/crates/js-component-bindgen-component/wit/js-component-bindgen.wit
@@ -58,13 +58,29 @@ world js-component-bindgen {
     /// Whether to generate namespaced exports like `foo as "local:package/foo"`.
     /// These exports can break typescript builds.
     no-namespaced-exports: option<bool>,
-    
+
     /// Whether to generate module declarations like `declare module "local:package/foo" {...`.
     guest: option<bool>,
 
     /// Whether to output core Wasm utilizing multi-memory or to polyfill
     /// this handling.
     multi-memory: option<bool>,
+
+    /// Configure whether to use `async` imports or exports with
+    /// JavaScript Promise Integration (JSPI).
+    async-mode: option<async-mode>,
+  }
+
+  record async-imports-exports {
+    imports: list<string>,
+    exports: list<string>,
+  }
+
+  variant async-mode {
+    /// default to sync mode
+    sync,
+    /// use JavaScript Promise Integration (JSPI)
+    jspi(async-imports-exports),
   }
 
   variant wit {
@@ -96,6 +112,9 @@ world js-component-bindgen {
     features: option<enabled-feature-set>,
     /// Whether to generate module declarations like `declare module "local:package/foo" {...`.
     guest: option<bool>,
+    /// Configure whether to use `async` imports or exports with
+    /// JavaScript Promise Integration (JSPI).
+    async-mode: option<async-mode>,
   }
 
   enum export-type {
diff --git a/crates/js-component-bindgen/src/function_bindgen.rs b/crates/js-component-bindgen/src/function_bindgen.rs
index 514a2ed46..a0fbed3f4 100644
--- a/crates/js-component-bindgen/src/function_bindgen.rs
+++ b/crates/js-component-bindgen/src/function_bindgen.rs
@@ -86,6 +86,7 @@ pub struct FunctionBindgen<'a> {
     pub callee: &'a str,
     pub callee_resource_dynamic: bool,
     pub resolve: &'a Resolve,
+    pub is_async: bool,
 }
 
 impl FunctionBindgen<'_> {
@@ -1048,7 +1049,13 @@ impl Bindgen for FunctionBindgen<'_> {
             Instruction::CallWasm { sig, .. } => {
                 let sig_results_length = sig.results.len();
                 self.bind_results(sig_results_length, results);
-                uwriteln!(self.src, "{}({});", self.callee, operands.join(", "));
+                let maybe_async_await = if self.is_async { "await " } else { "" };
+                uwriteln!(
+                    self.src,
+                    "{maybe_async_await}{}({});",
+                    self.callee,
+                    operands.join(", ")
+                );
 
                 if let Some(prefix) = self.tracing_prefix {
                     let to_result_string = self.intrinsic(Intrinsic::ToResultString);
@@ -1066,15 +1073,20 @@ impl Bindgen for FunctionBindgen<'_> {
 
             Instruction::CallInterface { func } => {
                 let results_length = func.results.len();
+                let maybe_async_await = if self.is_async { "await " } else { "" };
                 let call = if self.callee_resource_dynamic {
                     format!(
-                        "{}.{}({})",
+                        "{maybe_async_await}{}.{}({})",
                         operands[0],
                         self.callee,
                         operands[1..].join(", ")
                     )
                 } else {
-                    format!("{}({})", self.callee, operands.join(", "))
+                    format!(
+                        "{maybe_async_await}{}({})",
+                        self.callee,
+                        operands.join(", ")
+                    )
                 };
                 if self.err == ErrHandling::ResultCatchHandler {
                     // result<_, string> allows JS error coercion only, while
diff --git a/crates/js-component-bindgen/src/intrinsics.rs b/crates/js-component-bindgen/src/intrinsics.rs
index 413c6da9d..5e27da73e 100644
--- a/crates/js-component-bindgen/src/intrinsics.rs
+++ b/crates/js-component-bindgen/src/intrinsics.rs
@@ -671,6 +671,7 @@ impl Intrinsic {
             "hasOwnProperty",
             "i32ToF32",
             "i64ToF64",
+            "imports",
             "instantiateCore",
             "isLE",
             "resourceCallBorrows",
diff --git a/crates/js-component-bindgen/src/lib.rs b/crates/js-component-bindgen/src/lib.rs
index 827915531..2c52cabd9 100644
--- a/crates/js-component-bindgen/src/lib.rs
+++ b/crates/js-component-bindgen/src/lib.rs
@@ -8,7 +8,7 @@ pub mod function_bindgen;
 pub mod intrinsics;
 pub mod names;
 pub mod source;
-pub use transpile_bindgen::{BindingsMode, InstantiationMode, TranspileOpts};
+pub use transpile_bindgen::{AsyncMode, BindingsMode, InstantiationMode, TranspileOpts};
 
 use anyhow::Result;
 use transpile_bindgen::transpile_bindgen;
diff --git a/crates/js-component-bindgen/src/transpile_bindgen.rs b/crates/js-component-bindgen/src/transpile_bindgen.rs
index 00cb6af61..63aff83a0 100644
--- a/crates/js-component-bindgen/src/transpile_bindgen.rs
+++ b/crates/js-component-bindgen/src/transpile_bindgen.rs
@@ -11,7 +11,7 @@ use crate::{uwrite, uwriteln};
 use base64::{engine::general_purpose, Engine as _};
 use heck::*;
 use std::cell::RefCell;
-use std::collections::{BTreeMap, BTreeSet, HashMap};
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::fmt::Write;
 use std::mem;
 use wasmtime_environ::component::{ExportIndex, NameMap, NameMapNoIntern, Transcode};
@@ -70,6 +70,19 @@ pub struct TranspileOpts {
     pub multi_memory: bool,
     /// Whether to generate types for a guest module using module declarations.
     pub guest: bool,
+    /// Configure whether to use `async` imports or exports with
+    /// JavaScript Promise Integration (JSPI).
+    pub async_mode: Option<AsyncMode>,
+}
+
+#[derive(Default, Clone, Debug)]
+pub enum AsyncMode {
+    #[default]
+    Sync,
+    JavaScriptPromiseIntegration {
+        imports: Vec<String>,
+        exports: Vec<String>,
+    },
 }
 
 #[derive(Default, Clone, Debug)]
@@ -117,6 +130,10 @@ struct JsBindgen<'a> {
 
     /// List of all intrinsics emitted to `src` so far.
     all_intrinsics: BTreeSet<Intrinsic>,
+
+    /// List of all core Wasm exported functions (and if is async) referenced in
+    /// `src` so far.
+    all_core_exported_funcs: Vec<(String, bool)>,
 }
 
 #[allow(clippy::too_many_arguments)]
@@ -130,6 +147,13 @@ pub fn transpile_bindgen(
     opts: TranspileOpts,
     files: &mut Files,
 ) -> (Vec<String>, Vec<(String, Export)>) {
+    let (async_imports, async_exports) = match opts.async_mode.clone() {
+        None | Some(AsyncMode::Sync) => (Default::default(), Default::default()),
+        Some(AsyncMode::JavaScriptPromiseIntegration { imports, exports }) => {
+            (imports.into_iter().collect(), exports.into_iter().collect())
+        }
+    };
+
     let mut bindgen = JsBindgen {
         local_names: LocalNames::default(),
         src: Source::default(),
@@ -137,6 +161,7 @@ pub fn transpile_bindgen(
         core_module_cnt: 0,
         opts: &opts,
         all_intrinsics: BTreeSet::new(),
+        all_core_exported_funcs: Vec::new(),
     };
     bindgen
         .local_names
@@ -157,6 +182,8 @@ pub fn transpile_bindgen(
         translation: component,
         component: &component.component,
         types,
+        async_imports,
+        async_exports,
         imports: Default::default(),
         exports: Default::default(),
         lowering_options: Default::default(),
@@ -216,7 +243,7 @@ pub fn transpile_bindgen(
     (bindgen.esm_bindgen.import_specifiers(), exports)
 }
 
-impl<'a> JsBindgen<'a> {
+impl JsBindgen<'_> {
     fn finish_component(
         &mut self,
         name: &str,
@@ -226,6 +253,28 @@ impl<'a> JsBindgen<'a> {
     ) {
         let mut output = source::Source::default();
         let mut compilation_promises = source::Source::default();
+        let mut core_exported_funcs = source::Source::default();
+
+        for (core_export_fn, is_async) in self.all_core_exported_funcs.iter() {
+            let local_name = self.local_names.get(core_export_fn);
+            if *is_async {
+                uwriteln!(
+                    core_exported_funcs,
+                    "{local_name} = WebAssembly.promising({core_export_fn});",
+                );
+            } else {
+                uwriteln!(core_exported_funcs, "{local_name} = {core_export_fn};",);
+            }
+        }
+
+        // adds a default implementation of `getCoreModule`
+        if matches!(self.opts.instantiation, Some(InstantiationMode::Async)) {
+            uwriteln!(
+                compilation_promises,
+                "if (!getCoreModule) getCoreModule = (name) => {}(new URL(`./${{name}}`, import.meta.url));",
+                self.intrinsic(Intrinsic::FetchCompile)
+            );
+        }
 
         // Setup the compilation data and compilation promises
         let mut removed = BTreeSet::new();
@@ -298,6 +347,7 @@ impl<'a> JsBindgen<'a> {
             .render_imports(&mut output, imports_object, &mut self.local_names);
 
         if self.opts.instantiation.is_some() {
+            uwrite!(&mut self.src.js, "{}", &core_exported_funcs as &str);
             self.esm_bindgen.render_exports(
                 &mut self.src.js,
                 self.opts.instantiation.is_some(),
@@ -366,6 +416,7 @@ impl<'a> JsBindgen<'a> {
                         let gen = (function* init () {{
                             {}\
                             {}\
+                            {}\
                         }})();
                         let promise, resolve, reject;
                         function runNext (value) {{
@@ -396,6 +447,7 @@ impl<'a> JsBindgen<'a> {
                 &self.src.js as &str,
                 &compilation_promises as &str,
                 &self.src.js_init as &str,
+                &core_exported_funcs as &str,
             );
 
             self.esm_bindgen.render_exports(
@@ -443,6 +495,8 @@ struct Instantiator<'a, 'b> {
     /// Instance flags which references have been emitted externally at least once.
     used_instance_flags: RefCell<BTreeSet<RuntimeComponentInstanceIndex>>,
     defined_resource_classes: BTreeSet<String>,
+    async_imports: HashSet<String>,
+    async_exports: HashSet<String>,
     lowering_options:
         PrimaryMap<LoweredIndex, (&'a CanonicalOptions, TrampolineIndex, TypeFuncIndex)>,
 }
@@ -1018,7 +1072,7 @@ impl<'a> Instantiator<'a, '_> {
                 uwriteln!(
                     self.src.js_init,
                     "({{ exports: exports{iu32} }} = yield {instantiate}(yield module{}{imports}));",
-                    idx.as_u32()
+                    idx.as_u32(),
                 )
             }
 
@@ -1026,7 +1080,7 @@ impl<'a> Instantiator<'a, '_> {
                 uwriteln!(
                     self.src.js_init,
                     "({{ exports: exports{iu32} }} = {instantiate}(module{}{imports}));",
-                    idx.as_u32()
+                    idx.as_u32(),
                 )
             }
         }
@@ -1097,6 +1151,17 @@ impl<'a> Instantiator<'a, '_> {
                 WorldItem::Type(_) => unreachable!(),
             };
 
+        let is_async = self
+            .async_imports
+            .contains(&format!("{import_name}#{func_name}"))
+            || import_name
+                .find('@')
+                .map(|i| {
+                    self.async_imports
+                        .contains(&format!("{}#{func_name}", import_name.get(0..i).unwrap()))
+                })
+                .unwrap_or(false);
+
         // nested interfaces only currently possible through mapping
         let (import_specifier, maybe_iface_member) = map_import(
             &self.gen.opts.map,
@@ -1178,7 +1243,15 @@ impl<'a> Instantiator<'a, '_> {
             .len();
         match self.gen.opts.import_bindings {
             None | Some(BindingsMode::Js) | Some(BindingsMode::Hybrid) => {
-                uwrite!(self.src.js, "\nfunction trampoline{}", trampoline.as_u32());
+                if is_async {
+                    uwrite!(
+                        self.src.js,
+                        "\nconst trampoline{} = new WebAssembly.Suspending(async function",
+                        trampoline.as_u32()
+                    );
+                } else {
+                    uwrite!(self.src.js, "\nfunction trampoline{}", trampoline.as_u32());
+                }
                 self.bindgen(
                     nparams,
                     call_type,
@@ -1192,8 +1265,14 @@ impl<'a> Instantiator<'a, '_> {
                     func,
                     &resource_map,
                     AbiVariant::GuestImport,
+                    is_async,
                 );
                 uwriteln!(self.src.js, "");
+                if is_async {
+                    uwriteln!(self.src.js, ");");
+                } else {
+                    uwriteln!(self.src.js, "");
+                }
             }
             Some(BindingsMode::Optimized) | Some(BindingsMode::DirectOptimized) => {
                 uwriteln!(self.src.js, "let trampoline{};", trampoline.as_u32());
@@ -1556,6 +1635,7 @@ impl<'a> Instantiator<'a, '_> {
         func: &Function,
         resource_map: &ResourceMap,
         abi: AbiVariant,
+        is_async: bool,
     ) {
         let memory = opts.memory.map(|idx| format!("memory{}", idx.as_u32()));
         let realloc = opts.realloc.map(|idx| format!("realloc{}", idx.as_u32()));
@@ -1650,6 +1730,7 @@ impl<'a> Instantiator<'a, '_> {
             },
             src: source::Source::default(),
             resolve: self.resolve,
+            is_async,
         };
         abi::call(
             self.resolve,
@@ -1930,14 +2011,50 @@ impl<'a> Instantiator<'a, '_> {
         export_name: &String,
         resource_map: &ResourceMap,
     ) {
+        let is_async = self.async_exports.contains(&func.name)
+            || self
+                .async_exports
+                .contains(&format!("{export_name}#{}", func.name))
+            || export_name
+                .find('@')
+                .map(|i| {
+                    self.async_exports.contains(&format!(
+                        "{}#{}",
+                        export_name.get(0..i).unwrap(),
+                        func.name
+                    ))
+                })
+                .unwrap_or(false);
+
+        let maybe_async = if is_async { "async " } else { "" };
+
+        let core_export_fn = self.core_def(def);
+        let callee = match self
+            .gen
+            .local_names
+            .get_or_create(&core_export_fn, &core_export_fn)
+        {
+            (local_name, true) => local_name.to_string(),
+            (local_name, false) => {
+                let local_name = local_name.to_string();
+                uwriteln!(self.src.js, "let {local_name};");
+                self.gen
+                    .all_core_exported_funcs
+                    .push((core_export_fn.clone(), is_async));
+                local_name
+            }
+        };
+
         match func.kind {
-            FunctionKind::Freestanding => uwrite!(self.src.js, "\nfunction {local_name}"),
+            FunctionKind::Freestanding => {
+                uwrite!(self.src.js, "\n{maybe_async}function {local_name}")
+            }
             FunctionKind::Method(_) => {
                 self.ensure_local_resource_class(local_name.to_string());
                 let method_name = func.item_name().to_lower_camel_case();
                 uwrite!(
                     self.src.js,
-                    "\n{local_name}.prototype.{method_name} = function {}",
+                    "\n{local_name}.prototype.{method_name} = {maybe_async}function {}",
                     if !is_js_reserved_word(&method_name) {
                         method_name.to_string()
                     } else {
@@ -1971,7 +2088,6 @@ impl<'a> Instantiator<'a, '_> {
                 self.defined_resource_classes.insert(local_name.to_string());
             }
         }
-        let callee = self.core_def(def);
         self.bindgen(
             func.params.len(),
             match func.kind {
@@ -1988,6 +2104,7 @@ impl<'a> Instantiator<'a, '_> {
             func,
             resource_map,
             AbiVariant::GuestExport,
+            is_async,
         );
         match func.kind {
             FunctionKind::Freestanding => self.src.js("\n"),
diff --git a/crates/js-component-bindgen/src/ts_bindgen.rs b/crates/js-component-bindgen/src/ts_bindgen.rs
index 9d7f4313b..ad8da317a 100644
--- a/crates/js-component-bindgen/src/ts_bindgen.rs
+++ b/crates/js-component-bindgen/src/ts_bindgen.rs
@@ -2,7 +2,7 @@ use crate::files::Files;
 use crate::function_bindgen::{array_ty, as_nullable, maybe_null};
 use crate::names::{is_js_identifier, maybe_quote_id, LocalNames, RESERVED_KEYWORDS};
 use crate::source::Source;
-use crate::transpile_bindgen::{parse_world_key, InstantiationMode, TranspileOpts};
+use crate::transpile_bindgen::{parse_world_key, AsyncMode, InstantiationMode, TranspileOpts};
 use crate::{dealias, feature_gate_allowed, uwrite, uwriteln};
 use anyhow::{Context as _, Result};
 use heck::*;
@@ -32,6 +32,9 @@ struct TsBindgen {
 
     /// Whether or not the types should be generated for a guest module
     guest: bool,
+
+    async_imports: HashSet<String>,
+    async_exports: HashSet<String>,
 }
 
 /// Used to generate a `*.d.ts` file for each imported and exported interface for
@@ -57,6 +60,12 @@ pub fn ts_bindgen(
     opts: &TranspileOpts,
     files: &mut Files,
 ) -> Result<()> {
+    let (async_imports, async_exports) = match opts.async_mode.clone() {
+        None | Some(AsyncMode::Sync) => (Default::default(), Default::default()),
+        Some(AsyncMode::JavaScriptPromiseIntegration { imports, exports }) => {
+            (imports.into_iter().collect(), exports.into_iter().collect())
+        }
+    };
     let mut bindgen = TsBindgen {
         src: Source::default(),
         interface_names: LocalNames::default(),
@@ -64,6 +73,8 @@ pub fn ts_bindgen(
         import_object: Source::default(),
         export_object: Source::default(),
         guest: opts.guest,
+        async_imports,
+        async_exports,
     };
 
     let world = &resolve.worlds[id];
@@ -373,7 +384,7 @@ impl TsBindgen {
         files: &mut Files,
     ) -> String {
         // in case an imported type is used as an exported type
-        let local_name = self.generate_interface(name, resolve, id, files);
+        let local_name = self.generate_interface(name, resolve, id, files, false);
         uwriteln!(
             self.import_object,
             "{}: typeof {local_name},",
@@ -393,7 +404,7 @@ impl TsBindgen {
             if iface_name == "*" {
                 uwrite!(self.import_object, "{}: ", maybe_quote_id(import_name));
                 let name = resolve.interfaces[id].name.as_ref().unwrap();
-                let local_name = self.generate_interface(name, resolve, id, files);
+                let local_name = self.generate_interface(name, resolve, id, files, false);
                 uwriteln!(self.import_object, "typeof {local_name},",);
                 return;
             }
@@ -401,7 +412,7 @@ impl TsBindgen {
         uwriteln!(self.import_object, "{}: {{", maybe_quote_id(import_name));
         for (iface_name, &id) in ifaces {
             let name = resolve.interfaces[id].name.as_ref().unwrap();
-            let local_name = self.generate_interface(name, resolve, id, files);
+            let local_name = self.generate_interface(name, resolve, id, files, false);
             uwriteln!(
                 self.import_object,
                 "{}: typeof {local_name},",
@@ -420,7 +431,7 @@ impl TsBindgen {
     ) {
         uwriteln!(self.import_object, "{}: {{", maybe_quote_id(import_name));
         let mut gen = TsInterface::new(resolve, false);
-        gen.ts_func(func, true, false);
+        gen.ts_func(func, true, false, false);
         let src = gen.finish();
         self.import_object.push_str(&src);
         uwriteln!(self.import_object, "}},");
@@ -434,7 +445,7 @@ impl TsBindgen {
         files: &mut Files,
         instantiation: bool,
     ) -> String {
-        let local_name = self.generate_interface(export_name, resolve, id, files);
+        let local_name = self.generate_interface(export_name, resolve, id, files, false);
         if instantiation {
             uwriteln!(
                 self.export_object,
@@ -458,14 +469,26 @@ impl TsBindgen {
     fn export_funcs(
         &mut self,
         resolve: &Resolve,
-        _world: WorldId,
+        world: WorldId,
         funcs: &[(String, &Function)],
         _files: &mut Files,
         declaration: bool,
     ) {
         let mut gen = TsInterface::new(resolve, false);
+        let async_exports = self.async_exports.clone();
+        let id_name = &resolve.worlds[world].name;
         for (_, func) in funcs {
-            gen.ts_func(func, false, declaration);
+            let func_name = &func.name;
+            let is_async = async_exports.contains(func_name)
+                || async_exports.contains(&format!("{id_name}#{func_name}"))
+                || id_name
+                    .find('@')
+                    .map(|i| {
+                        async_exports
+                            .contains(&format!("{}#{func_name}", id_name.get(0..i).unwrap()))
+                    })
+                    .unwrap_or(false);
+            gen.ts_func(func, false, declaration, is_async);
         }
         let src = gen.finish();
         self.export_object.push_str(&src);
@@ -477,6 +500,7 @@ impl TsBindgen {
         resolve: &Resolve,
         id: InterfaceId,
         files: &mut Files,
+        is_world_export: bool,
     ) -> String {
         let iface = resolve
             .interfaces
@@ -525,6 +549,12 @@ impl TsBindgen {
             return local_name;
         }
 
+        let async_funcs = if is_world_export {
+            self.async_exports.clone()
+        } else {
+            self.async_imports.clone()
+        };
+
         let module_or_namespace = if self.guest {
             format!("declare module '{id_name}' {{")
         } else {
@@ -541,7 +571,16 @@ impl TsBindgen {
             {
                 continue;
             }
-            gen.ts_func(func, false, true);
+            let func_name = &func.name;
+            let is_async = is_world_export && async_funcs.contains(func_name)
+                || async_funcs.contains(&format!("{id_name}#{func_name}"))
+                || id_name
+                    .find('@')
+                    .map(|i| {
+                        async_funcs.contains(&format!("{}#{func_name}", id_name.get(0..i).unwrap()))
+                    })
+                    .unwrap_or(false);
+            gen.ts_func(func, false, true, is_async);
         }
         // Export resources for the interface
         for (_, ty) in resolve.interfaces[id].types.iter() {
@@ -735,7 +774,7 @@ impl<'a> TsInterface<'a> {
         self.src.push_str("]");
     }
 
-    fn ts_func(&mut self, func: &Function, default: bool, declaration: bool) {
+    fn ts_func(&mut self, func: &Function, default: bool, declaration: bool, is_async: bool) {
         let iface = if let FunctionKind::Method(ty)
         | FunctionKind::Static(ty)
         | FunctionKind::Constructor(ty) = func.kind
@@ -760,11 +799,15 @@ impl<'a> TsInterface<'a> {
             func.item_name().to_lower_camel_case()
         };
 
+        let maybe_async = if is_async { "async " } else { "" };
+
         if declaration {
             match func.kind {
                 FunctionKind::Freestanding => {
                     if is_js_identifier(&out_name) {
-                        iface.src.push_str(&format!("export function {out_name}"));
+                        iface
+                            .src
+                            .push_str(&format!("export {maybe_async}function {out_name}"));
                     } else {
                         let (local_name, _) = iface.local_names.get_or_create(&out_name, &out_name);
                         iface
@@ -772,21 +815,25 @@ impl<'a> TsInterface<'a> {
                             .push_str(&format!("export {{ {local_name} as {out_name} }};\n"));
                         iface
                             .src
-                            .push_str(&format!("declare function {local_name}"));
+                            .push_str(&format!("declare {maybe_async}function {local_name}"));
                     };
                 }
                 FunctionKind::Method(_) => {
                     if is_js_identifier(&out_name) {
-                        iface.src.push_str(&out_name);
+                        iface.src.push_str(&format!("{maybe_async}{out_name}"));
                     } else {
-                        iface.src.push_str(&format!("'{out_name}'"));
+                        iface.src.push_str(&format!("{maybe_async}'{out_name}'"));
                     }
                 }
                 FunctionKind::Static(_) => {
                     if is_js_identifier(&out_name) {
-                        iface.src.push_str(&format!("static {out_name}"))
+                        iface
+                            .src
+                            .push_str(&format!("static {maybe_async}{out_name}"))
                     } else {
-                        iface.src.push_str(&format!("static '{out_name}'"))
+                        iface
+                            .src
+                            .push_str(&format!("static {maybe_async}'{out_name}'"))
                     }
                 }
                 FunctionKind::Constructor(_) => {
@@ -795,9 +842,9 @@ impl<'a> TsInterface<'a> {
                 }
             }
         } else if is_js_identifier(&out_name) {
-            iface.src.push_str(&out_name);
+            iface.src.push_str(&format!("{maybe_async}{out_name}"));
         } else {
-            iface.src.push_str(&format!("'{out_name}'"));
+            iface.src.push_str(&format!("{maybe_async}'{out_name}'"));
         }
 
         let end_character = if declaration { ';' } else { ',' };
@@ -834,6 +881,10 @@ impl<'a> TsInterface<'a> {
         }
         iface.src.push_str(": ");
 
+        if is_async {
+            iface.src.push_str("Promise<");
+        }
+
         if let Some((ok_ty, _)) = func.results.throws(iface.resolve) {
             iface.print_optional_ty(ok_ty);
         } else {
@@ -852,6 +903,12 @@ impl<'a> TsInterface<'a> {
                 }
             }
         }
+
+        if is_async {
+            // closes `Promise<>`
+            iface.src.push_str(">");
+        }
+
         iface.src.push_str(format!("{}\n", end_character).as_str());
     }
 
diff --git a/docs/src/transpiling.md b/docs/src/transpiling.md
index fd88b0b26..91cc4f003 100644
--- a/docs/src/transpiling.md
+++ b/docs/src/transpiling.md
@@ -53,6 +53,10 @@ Options include:
 * `--tracing`: Emit tracing calls for all function entry and exits.
 * `--no-namespaced-exports`: Removes exports of the type `test as "test:flavorful/test"` which are not compatible with typescript
 
+* `--async-mode [mode]`: EXPERIMENTAL: For the component imports and exports, functions and methods on resources can be specified as `async`. The only option is `jspi` (JavaScript Promise Integration).
+* `--async-imports <imports...>`: EXPERIMENTAL: Specify the component imports as `async`. Used with `--async-mode`.
+* `--async-exports <exports...>`: EXPERIMENTAL: Specify the component exports as `async`. Used with `--async-mode`.
+
 ## Browser Support
 
 Jco itself can be used in the browser, which provides the simpler Jco API that is just exactly the same
diff --git a/package-lock.json b/package-lock.json
index 7d88b341c..fca6e1e94 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -406,9 +406,9 @@
       }
     },
     "node_modules/@eslint/js": {
-      "version": "9.18.0",
-      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-9.18.0.tgz",
-      "integrity": "sha512-fK6L7rxcq6/z+AaQMtiFTkvbHkBLNlwyRxHpKawP0x3u9+NC6MQTnFW+AdpwC6gfHTW0051cokQgtTN2FqlxQA==",
+      "version": "9.19.0",
+      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-9.19.0.tgz",
+      "integrity": "sha512-rbq9/g38qjfqFLOVPvwjIvFFdNziEC5S65jmjPw5r6A//QH+W91akh9irMwjDN8zKUTak6W9EsAv4m/7Wnw0UQ==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -1061,9 +1061,9 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "20.17.14",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.17.14.tgz",
-      "integrity": "sha512-w6qdYetNL5KRBiSClK/KWai+2IMEJuAj+EujKCumalFOwXtvOXaEan9AuwcRID2IcOIAWSIfR495hBtgKlx2zg==",
+      "version": "20.17.16",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.17.16.tgz",
+      "integrity": "sha512-vOTpLduLkZXePLxHiHsBLp98mHGnl8RptV4YAO3HfKO5UHjDvySGbxKtpYfy8Sx5+WKcgc45qNreJJRVM3L6mw==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -1082,17 +1082,17 @@
       }
     },
     "node_modules/@typescript-eslint/eslint-plugin": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.21.0.tgz",
-      "integrity": "sha512-eTH+UOR4I7WbdQnG4Z48ebIA6Bgi7WO8HvFEneeYBxG8qCOYgTOFPSg6ek9ITIDvGjDQzWHcoWHCDO2biByNzA==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.22.0.tgz",
+      "integrity": "sha512-4Uta6REnz/xEJMvwf72wdUnC3rr4jAQf5jnTkeRQ9b6soxLxhDEbS/pfMPoJLDfFPNVRdryqWUIV/2GZzDJFZw==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
         "@eslint-community/regexpp": "^4.10.0",
-        "@typescript-eslint/scope-manager": "8.21.0",
-        "@typescript-eslint/type-utils": "8.21.0",
-        "@typescript-eslint/utils": "8.21.0",
-        "@typescript-eslint/visitor-keys": "8.21.0",
+        "@typescript-eslint/scope-manager": "8.22.0",
+        "@typescript-eslint/type-utils": "8.22.0",
+        "@typescript-eslint/utils": "8.22.0",
+        "@typescript-eslint/visitor-keys": "8.22.0",
         "graphemer": "^1.4.0",
         "ignore": "^5.3.1",
         "natural-compare": "^1.4.0",
@@ -1112,16 +1112,16 @@
       }
     },
     "node_modules/@typescript-eslint/parser": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/parser/-/parser-8.21.0.tgz",
-      "integrity": "sha512-Wy+/sdEH9kI3w9civgACwabHbKl+qIOu0uFZ9IMKzX3Jpv9og0ZBJrZExGrPpFAY7rWsXuxs5e7CPPP17A4eYA==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/parser/-/parser-8.22.0.tgz",
+      "integrity": "sha512-MqtmbdNEdoNxTPzpWiWnqNac54h8JDAmkWtJExBVVnSrSmi9z+sZUt0LfKqk9rjqmKOIeRhO4fHHJ1nQIjduIQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@typescript-eslint/scope-manager": "8.21.0",
-        "@typescript-eslint/types": "8.21.0",
-        "@typescript-eslint/typescript-estree": "8.21.0",
-        "@typescript-eslint/visitor-keys": "8.21.0",
+        "@typescript-eslint/scope-manager": "8.22.0",
+        "@typescript-eslint/types": "8.22.0",
+        "@typescript-eslint/typescript-estree": "8.22.0",
+        "@typescript-eslint/visitor-keys": "8.22.0",
         "debug": "^4.3.4"
       },
       "engines": {
@@ -1137,14 +1137,14 @@
       }
     },
     "node_modules/@typescript-eslint/scope-manager": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/scope-manager/-/scope-manager-8.21.0.tgz",
-      "integrity": "sha512-G3IBKz0/0IPfdeGRMbp+4rbjfSSdnGkXsM/pFZA8zM9t9klXDnB/YnKOBQ0GoPmoROa4bCq2NeHgJa5ydsQ4mA==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/scope-manager/-/scope-manager-8.22.0.tgz",
+      "integrity": "sha512-/lwVV0UYgkj7wPSw0o8URy6YI64QmcOdwHuGuxWIYznO6d45ER0wXUbksr9pYdViAofpUCNJx/tAzNukgvaaiQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@typescript-eslint/types": "8.21.0",
-        "@typescript-eslint/visitor-keys": "8.21.0"
+        "@typescript-eslint/types": "8.22.0",
+        "@typescript-eslint/visitor-keys": "8.22.0"
       },
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
@@ -1155,14 +1155,14 @@
       }
     },
     "node_modules/@typescript-eslint/type-utils": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/type-utils/-/type-utils-8.21.0.tgz",
-      "integrity": "sha512-95OsL6J2BtzoBxHicoXHxgk3z+9P3BEcQTpBKriqiYzLKnM2DeSqs+sndMKdamU8FosiadQFT3D+BSL9EKnAJQ==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/type-utils/-/type-utils-8.22.0.tgz",
+      "integrity": "sha512-NzE3aB62fDEaGjaAYZE4LH7I1MUwHooQ98Byq0G0y3kkibPJQIXVUspzlFOmOfHhiDLwKzMlWxaNv+/qcZurJA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@typescript-eslint/typescript-estree": "8.21.0",
-        "@typescript-eslint/utils": "8.21.0",
+        "@typescript-eslint/typescript-estree": "8.22.0",
+        "@typescript-eslint/utils": "8.22.0",
         "debug": "^4.3.4",
         "ts-api-utils": "^2.0.0"
       },
@@ -1179,9 +1179,9 @@
       }
     },
     "node_modules/@typescript-eslint/types": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-8.21.0.tgz",
-      "integrity": "sha512-PAL6LUuQwotLW2a8VsySDBwYMm129vFm4tMVlylzdoTybTHaAi0oBp7Ac6LhSrHHOdLM3efH+nAR6hAWoMF89A==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-8.22.0.tgz",
+      "integrity": "sha512-0S4M4baNzp612zwpD4YOieP3VowOARgK2EkN/GBn95hpyF8E2fbMT55sRHWBq+Huaqk3b3XK+rxxlM8sPgGM6A==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -1193,14 +1193,14 @@
       }
     },
     "node_modules/@typescript-eslint/typescript-estree": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-8.21.0.tgz",
-      "integrity": "sha512-x+aeKh/AjAArSauz0GiQZsjT8ciadNMHdkUSwBB9Z6PrKc/4knM4g3UfHml6oDJmKC88a6//cdxnO/+P2LkMcg==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-8.22.0.tgz",
+      "integrity": "sha512-SJX99NAS2ugGOzpyhMza/tX+zDwjvwAtQFLsBo3GQxiGcvaKlqGBkmZ+Y1IdiSi9h4Q0Lr5ey+Cp9CGWNY/F/w==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@typescript-eslint/types": "8.21.0",
-        "@typescript-eslint/visitor-keys": "8.21.0",
+        "@typescript-eslint/types": "8.22.0",
+        "@typescript-eslint/visitor-keys": "8.22.0",
         "debug": "^4.3.4",
         "fast-glob": "^3.3.2",
         "is-glob": "^4.0.3",
@@ -1220,16 +1220,16 @@
       }
     },
     "node_modules/@typescript-eslint/utils": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/utils/-/utils-8.21.0.tgz",
-      "integrity": "sha512-xcXBfcq0Kaxgj7dwejMbFyq7IOHgpNMtVuDveK7w3ZGwG9owKzhALVwKpTF2yrZmEwl9SWdetf3fxNzJQaVuxw==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/utils/-/utils-8.22.0.tgz",
+      "integrity": "sha512-T8oc1MbF8L+Bk2msAvCUzjxVB2Z2f+vXYfcucE2wOmYs7ZUwco5Ep0fYZw8quNwOiw9K8GYVL+Kgc2pETNTLOg==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.4.0",
-        "@typescript-eslint/scope-manager": "8.21.0",
-        "@typescript-eslint/types": "8.21.0",
-        "@typescript-eslint/typescript-estree": "8.21.0"
+        "@typescript-eslint/scope-manager": "8.22.0",
+        "@typescript-eslint/types": "8.22.0",
+        "@typescript-eslint/typescript-estree": "8.22.0"
       },
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
@@ -1244,13 +1244,13 @@
       }
     },
     "node_modules/@typescript-eslint/visitor-keys": {
-      "version": "8.21.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/visitor-keys/-/visitor-keys-8.21.0.tgz",
-      "integrity": "sha512-BkLMNpdV6prozk8LlyK/SOoWLmUFi+ZD+pcqti9ILCbVvHGk1ui1g4jJOc2WDLaeExz2qWwojxlPce5PljcT3w==",
+      "version": "8.22.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/visitor-keys/-/visitor-keys-8.22.0.tgz",
+      "integrity": "sha512-AWpYAXnUgvLNabGTy3uBylkgZoosva/miNd1I8Bz3SjotmQPbVqhO4Cczo8AsZ44XVErEBPr/CRSgaj8sG7g0w==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@typescript-eslint/types": "8.21.0",
+        "@typescript-eslint/types": "8.22.0",
         "eslint-visitor-keys": "^4.2.0"
       },
       "engines": {
@@ -1728,9 +1728,9 @@
       }
     },
     "node_modules/chromium-bidi": {
-      "version": "0.12.0",
-      "resolved": "https://registry.npmjs.org/chromium-bidi/-/chromium-bidi-0.12.0.tgz",
-      "integrity": "sha512-xzXveJmX826GGq1MeE5okD8XxaDT8172CXByhFJ687eY65rbjOIebdbUuQh+jXKaNyGKI14Veb3KjLLmSueaxA==",
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/chromium-bidi/-/chromium-bidi-1.1.0.tgz",
+      "integrity": "sha512-HislCEczCuamWm3+55Lig9XKmMF13K+BGKum9rwtDAzgUAHT4h5jNwhDmD4U20VoVUG8ujnv9UZ89qiIf5uF8w==",
       "dev": true,
       "license": "Apache-2.0",
       "dependencies": {
@@ -2172,9 +2172,9 @@
       }
     },
     "node_modules/eslint": {
-      "version": "9.18.0",
-      "resolved": "https://registry.npmjs.org/eslint/-/eslint-9.18.0.tgz",
-      "integrity": "sha512-+waTfRWQlSbpt3KWE+CjrPPYnbq9kfZIYUqapc0uBXyjTp8aYXZDsUH16m39Ryq3NjAVP4tjuF7KaukeqoCoaA==",
+      "version": "9.19.0",
+      "resolved": "https://registry.npmjs.org/eslint/-/eslint-9.19.0.tgz",
+      "integrity": "sha512-ug92j0LepKlbbEv6hD911THhoRHmbdXt2gX+VDABAW/Ir7D3nqKdv5Pf5vtlyY6HQMTEP2skXY43ueqTCWssEA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -2183,7 +2183,7 @@
         "@eslint/config-array": "^0.19.0",
         "@eslint/core": "^0.10.0",
         "@eslint/eslintrc": "^3.2.0",
-        "@eslint/js": "9.18.0",
+        "@eslint/js": "9.19.0",
         "@eslint/plugin-kit": "^0.2.5",
         "@humanfs/node": "^0.16.6",
         "@humanwhocodes/module-importer": "^1.0.1",
@@ -3753,18 +3753,18 @@
       }
     },
     "node_modules/puppeteer": {
-      "version": "24.1.0",
-      "resolved": "https://registry.npmjs.org/puppeteer/-/puppeteer-24.1.0.tgz",
-      "integrity": "sha512-F+3yKILaosLToT7amR7LIkTKkKMR0EGQPjFBch+MtgS8vRPS+4cPnLJuXDVTfCj2NqfrCnShtOr7yD+9dEgHRQ==",
+      "version": "24.1.1",
+      "resolved": "https://registry.npmjs.org/puppeteer/-/puppeteer-24.1.1.tgz",
+      "integrity": "sha512-fuhceZ5HZuDXVuaMIRxUuDHfCJLmK0pXh8FlzVQ0/+OApStevxZhU5kAVeYFOEqeCF5OoAyZjcWbdQK27xW/9A==",
       "dev": true,
       "hasInstallScript": true,
       "license": "Apache-2.0",
       "dependencies": {
         "@puppeteer/browsers": "2.7.0",
-        "chromium-bidi": "0.12.0",
+        "chromium-bidi": "1.1.0",
         "cosmiconfig": "^9.0.0",
         "devtools-protocol": "0.0.1380148",
-        "puppeteer-core": "24.1.0",
+        "puppeteer-core": "24.1.1",
         "typed-query-selector": "^2.12.0"
       },
       "bin": {
@@ -3775,14 +3775,14 @@
       }
     },
     "node_modules/puppeteer-core": {
-      "version": "24.1.0",
-      "resolved": "https://registry.npmjs.org/puppeteer-core/-/puppeteer-core-24.1.0.tgz",
-      "integrity": "sha512-ReefWoQgqdyl67uWEBy/TMZ4mAB7hP0JB5HIxSE8B1ot/4ningX1gmzHCOSNfMbTiS/VJHCvaZAe3oJTXph7yw==",
+      "version": "24.1.1",
+      "resolved": "https://registry.npmjs.org/puppeteer-core/-/puppeteer-core-24.1.1.tgz",
+      "integrity": "sha512-7FF3gq6bpIsbq3I8mfbodXh3DCzXagoz3l2eGv1cXooYU4g0P4mcHQVHuBD4iSZPXNg8WjzlP5kmRwK9UvwF0A==",
       "dev": true,
       "license": "Apache-2.0",
       "dependencies": {
         "@puppeteer/browsers": "2.7.0",
-        "chromium-bidi": "0.11.0",
+        "chromium-bidi": "1.1.0",
         "debug": "^4.4.0",
         "devtools-protocol": "0.0.1380148",
         "typed-query-selector": "^2.12.0",
@@ -3792,30 +3792,6 @@
         "node": ">=18"
       }
     },
-    "node_modules/puppeteer-core/node_modules/chromium-bidi": {
-      "version": "0.11.0",
-      "resolved": "https://registry.npmjs.org/chromium-bidi/-/chromium-bidi-0.11.0.tgz",
-      "integrity": "sha512-6CJWHkNRoyZyjV9Rwv2lYONZf1Xm0IuDyNq97nwSsxxP3wf5Bwy15K5rOvVKMtJ127jJBmxFUanSAOjgFRxgrA==",
-      "dev": true,
-      "license": "Apache-2.0",
-      "dependencies": {
-        "mitt": "3.0.1",
-        "zod": "3.23.8"
-      },
-      "peerDependencies": {
-        "devtools-protocol": "*"
-      }
-    },
-    "node_modules/puppeteer-core/node_modules/zod": {
-      "version": "3.23.8",
-      "resolved": "https://registry.npmjs.org/zod/-/zod-3.23.8.tgz",
-      "integrity": "sha512-XBx9AXhXktjUqnepgTiE5flcKIYWi/rme0Eaj+5Y0lftuGBq+jyRu/md4WnuxqgP1ubdpNCsYEYPxrzVHD8d6g==",
-      "dev": true,
-      "license": "MIT",
-      "funding": {
-        "url": "https://github.com/sponsors/colinhacks"
-      }
-    },
     "node_modules/queue-microtask": {
       "version": "1.2.3",
       "resolved": "https://registry.npmjs.org/queue-microtask/-/queue-microtask-1.2.3.tgz",
diff --git a/package.json b/package.json
index 751164ebb..d9179869a 100644
--- a/package.json
+++ b/package.json
@@ -63,7 +63,7 @@
     "build:types:preview2-shim": "cargo xtask generate wasi-types",
     "lint": "eslint -c eslintrc.cjs src/**/*.js packages/*/lib/**/*.js",
     "test:lts": "mocha -u tdd test/test.js --timeout 240000",
-    "test": "node --stack-trace-limit=100 node_modules/mocha/bin/mocha.js -u tdd test/test.js --timeout 240000",
+    "test": "node --experimental-wasm-jspi --stack-trace-limit=100 node_modules/mocha/bin/mocha.js -u tdd test/test.js --timeout 240000",
     "prepublishOnly": "cargo xtask build release && npm run test"
   },
   "files": [
diff --git a/src/cmd/transpile.js b/src/cmd/transpile.js
index 1282be092..6bc109c7b 100644
--- a/src/cmd/transpile.js
+++ b/src/cmd/transpile.js
@@ -14,6 +14,22 @@ import { platform } from 'node:process';
 
 const isWindows = platform === 'win32';
 
+const ASYNC_WASI_IMPORTS = [
+  "wasi:io/poll#poll",
+  "wasi:io/poll#[method]pollable.block",
+  "wasi:io/streams#[method]input-stream.blocking-read",
+  "wasi:io/streams#[method]input-stream.blocking-skip",
+  "wasi:io/streams#[method]output-stream.blocking-flush",
+  "wasi:io/streams#[method]output-stream.blocking-write-and-flush",
+  "wasi:io/streams#[method]output-stream.blocking-write-zeroes-and-flush",
+  "wasi:io/streams#[method]output-stream.blocking-splice",
+];
+
+const ASYNC_WASI_EXPORTS = [
+  "wasi:cli/run#run",
+  "wasi:http/incoming-handler#handle",
+];
+
 export async function types (witPath, opts) {
   const files = await typesComponent(witPath, opts);
   await writeFiles(files, opts.quiet ? false : 'Generated Type Files');
@@ -31,6 +47,9 @@ export async function guestTypes (witPath, opts) {
  *   worldName?: string,
  *   instantiation?: 'async' | 'sync',
  *   tlaCompat?: bool,
+ *   asyncMode?: string,
+ *   asyncImports?: string[],
+ *   asyncExports?: string[],
  *   outDir?: string,
  *   features?: string[] | 'all',
  *   guest?: bool,
@@ -57,6 +76,21 @@ export async function typesComponent (witPath, opts) {
     features = { tag: 'list', val: opts.feature };
   }
 
+  if (opts.asyncWasiImports)
+    opts.asyncImports = ASYNC_WASI_IMPORTS.concat(opts.asyncImports || []);
+  if (opts.asyncWasiExports)
+    opts.asyncExports = ASYNC_WASI_EXPORTS.concat(opts.asyncExports || []);
+
+  const asyncMode = !opts.asyncMode || opts.asyncMode === 'sync' ?
+    null :
+    {
+      tag: opts.asyncMode,
+      val: {
+        imports: opts.asyncImports || [],
+        exports: opts.asyncExports || [],
+      },
+    };
+
   return Object.fromEntries(generateTypes(name, {
     wit: { tag: 'path', val: (isWindows ? '//?/' : '') + resolve(witPath) },
     instantiation,
@@ -64,6 +98,7 @@ export async function typesComponent (witPath, opts) {
     world: opts.worldName,
     features,
     guest: opts.guest ?? false,
+    asyncMode,
   }).map(([name, file]) => [`${outDir}${name}`, file]));
 }
 
@@ -105,6 +140,12 @@ export async function transpile (componentPath, opts, program) {
     opts.name = basename(componentPath.slice(0, -extname(componentPath).length || Infinity));
   if (opts.map)
     opts.map = Object.fromEntries(opts.map.map(mapping => mapping.split('=')));
+
+  if (opts.asyncWasiImports)
+    opts.asyncImports = ASYNC_WASI_IMPORTS.concat(opts.asyncImports || []);
+  if (opts.asyncWasiExports)
+    opts.asyncExports = ASYNC_WASI_EXPORTS.concat(opts.asyncExports || []);
+
   const { files } = await transpileComponent(component, opts);
   await writeFiles(files, opts.quiet ? false : 'Transpiled JS Component Files');
 }
@@ -133,6 +174,9 @@ async function wasm2Js (source) {
  *   instantiation?: 'async' | 'sync',
  *   importBindings?: 'js' | 'optimized' | 'hybrid' | 'direct-optimized',
  *   map?: Record<string, string>,
+ *   asyncMode?: string,
+ *   asyncImports?: string[],
+ *   asyncExports?: string[],
  *   validLiftingOptimization?: bool,
  *   tracing?: bool,
  *   nodejsCompat?: bool,
@@ -155,6 +199,7 @@ export async function transpileComponent (component, opts = {}) {
 
   let spinner;
   const showSpinner = getShowSpinner();
+
   if (opts.optimize) {
     if (showSpinner) setShowSpinner(true);
     ({ component } = await optimizeComponent(component, opts));
@@ -183,10 +228,21 @@ export async function transpileComponent (component, opts = {}) {
     instantiation = { tag: 'async' };
   }
 
+  const asyncMode = !opts.asyncMode || opts.asyncMode === 'sync' ?
+    null :
+    {
+      tag: opts.asyncMode,
+      val: {
+        imports: opts.asyncImports || [],
+        exports: opts.asyncExports || [],
+      },
+    };
+
   let { files, imports, exports } = generate(component, {
     name: opts.name ?? 'component',
     map: Object.entries(opts.map ?? {}),
     instantiation,
+    asyncMode,
     importBindings: opts.importBindings ? { tag: opts.importBindings } : null,
     validLiftingOptimization: opts.validLiftingOptimization ?? false,
     tracing: opts.tracing ?? false,
diff --git a/src/jco.js b/src/jco.js
index ff85e1e63..251c10a5a 100755
--- a/src/jco.js
+++ b/src/jco.js
@@ -52,6 +52,11 @@ program.command('transpile')
   .option('--no-typescript', 'do not output TypeScript .d.ts types')
   .option('--valid-lifting-optimization', 'optimize component binary validations assuming all lifted values are valid')
   .addOption(new Option('--import-bindings [mode]', 'bindings mode for imports').choices(['js', 'optimized', 'hybrid', 'direct-optimized']).preset('js'))
+  .addOption(new Option('--async-mode [mode]', 'EXPERIMENTAL: use async imports and exports').choices(['sync', 'jspi']).preset('sync'))
+  .option('--async-wasi-imports', 'EXPERIMENTAL: async component imports from WASI interfaces')
+  .option('--async-wasi-exports', 'EXPERIMENTAL: async component exports from WASI interfaces')
+  .option('--async-imports <imports...>', 'EXPERIMENTAL: async component imports (examples: "wasi:io/poll@0.2.0#poll", "wasi:io/poll#[method]pollable.block")')
+  .option('--async-exports <exports...>', 'EXPERIMENTAL: async component exports (examples: "wasi:cli/run@#run", "handle")')
   .option('--tracing', 'emit `tracing` calls on function entry/exit')
   .option('-b, --base64-cutoff <bytes>', 'set the byte size under which core Wasm binaries will be inlined as base64', myParseInt)
   .option('--tla-compat', 'enables compatibility for JS environments without top-level await support via an async $init promise export')
@@ -76,6 +81,11 @@ program.command('types')
   .requiredOption('-o, --out-dir <out-dir>', 'output directory')
   .option('--tla-compat', 'generates types for the TLA compat output with an async $init promise export')
   .addOption(new Option('-I, --instantiation [mode]', 'type output for custom module instantiation').choices(['async', 'sync']).preset('async'))
+  .addOption(new Option('--async-mode [mode]', 'EXPERIMENTAL: use async imports and exports').choices(['sync', 'jspi']).preset('sync'))
+  .option('--async-wasi-imports', 'EXPERIMENTAL: async component imports from WASI interfaces')
+  .option('--async-wasi-exports', 'EXPERIMENTAL: async component exports from WASI interfaces')
+  .option('--async-imports <imports...>', 'EXPERIMENTAL: async component imports (examples: "wasi:io/poll@0.2.0#poll", "wasi:io/poll#[method]pollable.block")')
+  .option('--async-exports <exports...>', 'EXPERIMENTAL: async component exports (examples: "wasi:cli/run@#run", "handle")')
   .option('-q, --quiet', 'disable output summary')
   .option('--feature <feature>', 'enable one specific WIT feature (repeatable)', collectOptions, [])
   .option('--all-features', 'enable all features')
diff --git a/test/async.browser.js b/test/async.browser.js
new file mode 100644
index 000000000..28f8e5f66
--- /dev/null
+++ b/test/async.browser.js
@@ -0,0 +1,153 @@
+import { dirname, join, resolve } from "node:path";
+import { execArgv } from "node:process";
+import { deepStrictEqual, ok, strictEqual, fail } from "node:assert";
+import { mkdir, readFile, rm, symlink, writeFile } from "node:fs/promises";
+
+import { fileURLToPath, pathToFileURL } from "url";
+import puppeteer from "puppeteer";
+
+import {
+  exec,
+  jcoPath,
+  getTmpDir,
+  setupAsyncTest,
+  startTestWebServer,
+  loadTestPage,
+} from "./helpers.js";
+
+const multiMemory = execArgv.includes("--experimental-wasm-multi-memory")
+  ? ["--multi-memory"]
+  : [];
+
+const AsyncFunction = (async () => {}).constructor;
+
+export async function asyncBrowserTest(_fixtures) {
+  suite("Async", () => {
+    var tmpDir;
+    var outDir;
+    var outFile;
+
+    suiteSetup(async function () {
+      tmpDir = await getTmpDir();
+      outDir = resolve(tmpDir, "out-component-dir");
+      outFile = resolve(tmpDir, "out-component-file");
+
+      const modulesDir = resolve(tmpDir, "node_modules", "@bytecodealliance");
+      await mkdir(modulesDir, { recursive: true });
+      await symlink(
+        fileURLToPath(new URL("../packages/preview2-shim", import.meta.url)),
+        resolve(modulesDir, "preview2-shim"),
+        "dir",
+      );
+    });
+
+    suiteTeardown(async function () {
+      try {
+        await rm(tmpDir, { recursive: true });
+      } catch {}
+    });
+
+    teardown(async function () {
+      try {
+        await rm(outDir, { recursive: true });
+        await rm(outFile);
+      } catch {}
+    });
+
+    if (typeof WebAssembly?.Suspending === "function") {
+      test("Transpile async (browser, JSPI)", async () => {
+        const componentName = "async-call";
+        const {
+          instance,
+          cleanup: componentCleanup,
+          outputDir,
+        } = await setupAsyncTest({
+          asyncMode: "jspi",
+          component: {
+            name: "async_call",
+            path: resolve("test/fixtures/components/async_call.component.wasm"),
+            imports: {
+              "something:test/test-interface": {
+                callAsync: async () => "called async",
+                callSync: () => "called sync",
+              },
+            },
+          },
+          jco: {
+            transpile: {
+              extraArgs: {
+                asyncImports: ["something:test/test-interface#call-async"],
+                asyncExports: ["run-async"],
+              },
+            },
+          },
+        });
+        const moduleName = componentName.toLowerCase().replaceAll("-", "_");
+        const moduleRelPath = `${moduleName}/${moduleName}.js`;
+
+        strictEqual(
+          instance.runSync instanceof AsyncFunction,
+          false,
+          "runSync() should be a sync function",
+        );
+        strictEqual(
+          instance.runAsync instanceof AsyncFunction,
+          true,
+          "runAsync() should be an async function",
+        );
+
+        // Start a test web server
+        const {
+          server,
+          serverPort,
+          cleanup: webServerCleanup,
+        } = await startTestWebServer({
+          routes: [
+            // NOTE: the goal here is to serve relative paths via the browser hash
+            //
+            // (1) browser visits test page (served by test web server)
+            // (2) browser requests component itself by looking at URL hash fragment
+            //     (i.e. "#transpiled:async_call/async_call.js" -> , "/transpiled/async_call/async_call.js")
+            //     (i.e. "/transpiled/async_call/async_call.js" -> file read of /tmp/xxxxxx/async_call/async_call.js)
+            {
+              urlPrefix: "/transpiled/",
+              basePathURL: pathToFileURL(`${outputDir}/`),
+            },
+            // Serve all other files (ex. the initial HTML for the page)
+            { basePathURL: import.meta.url },
+          ],
+        });
+
+        // Start a browser to visit the test server
+        const browser = await puppeteer.launch({
+          args: [
+            "--enable-experimental-webassembly-jspi",
+            "--flag-switches-begin",
+            "--enable-features=WebAssemblyExperimentalJSPI",
+            "--flag-switches-end",
+          ],
+        });
+
+        // Load the test page in the browser, which will trigger tests against
+        // the component and/or related browser polyfills
+        const {
+          page,
+          output: { json },
+        } = await loadTestPage({
+          browser,
+          serverPort,
+          path: "fixtures/browser/test-pages/something__test.async.html",
+          hash: `transpiled:${moduleRelPath}`,
+        });
+
+        // Check the output expected to be returned from handle of the
+        // guest export (this depends on the component)
+        deepStrictEqual(json, { responseText: "callAsync" });
+
+        await browser.close();
+        await webServerCleanup();
+        await componentCleanup();
+      });
+    }
+  });
+}
diff --git a/test/async.js b/test/async.js
new file mode 100644
index 000000000..2cd862661
--- /dev/null
+++ b/test/async.js
@@ -0,0 +1,143 @@
+import { join, resolve } from "node:path";
+import { execArgv } from "node:process";
+import { deepStrictEqual, ok, strictEqual, fail } from "node:assert";
+import { mkdir, readFile, rm, symlink, writeFile } from "node:fs/promises";
+
+import { fileURLToPath, pathToFileURL } from "url";
+
+import {
+  exec,
+  jcoPath,
+  getTmpDir,
+  setupAsyncTest,
+} from "./helpers.js";
+
+const multiMemory = execArgv.includes("--experimental-wasm-multi-memory")
+  ? ["--multi-memory"]
+  : [];
+
+const AsyncFunction = (async () => {}).constructor;
+
+export async function asyncTest(_fixtures) {
+  suite("Async", () => {
+    var tmpDir;
+    var outDir;
+    var outFile;
+
+    suiteSetup(async function () {
+      tmpDir = await getTmpDir();
+      outDir = resolve(tmpDir, "out-component-dir");
+      outFile = resolve(tmpDir, "out-component-file");
+
+      const modulesDir = resolve(tmpDir, "node_modules", "@bytecodealliance");
+      await mkdir(modulesDir, { recursive: true });
+      await symlink(
+        fileURLToPath(new URL("../packages/preview2-shim", import.meta.url)),
+        resolve(modulesDir, "preview2-shim"),
+        "dir",
+      );
+    });
+
+    suiteTeardown(async function () {
+      try {
+        await rm(tmpDir, { recursive: true });
+      } catch {}
+    });
+
+    teardown(async function () {
+      try {
+        await rm(outDir, { recursive: true });
+        await rm(outFile);
+      } catch {}
+    });
+
+    test("Transpile async", async () => {
+      const name = "flavorful";
+      const { stderr } = await exec(
+        jcoPath,
+        "transpile",
+        `test/fixtures/components/${name}.component.wasm`,
+        "--no-wasi-shim",
+        "--name",
+        name,
+        "-o",
+        outDir
+      );
+      strictEqual(stderr, "");
+      const source = await readFile(`${outDir}/${name}.js`);
+      ok(source.toString().includes("export { test"));
+    });
+
+    if (typeof WebAssembly?.Suspending === "function") {
+      test("Transpile async (NodeJS, JSPI)", async () => {
+        const { instance, cleanup, component } = await setupAsyncTest({
+          asyncMode: "jspi",
+          component: {
+            name: "async_call",
+            path: resolve("test/fixtures/components/async_call.component.wasm"),
+            imports: {
+              'something:test/test-interface': {
+                callAsync: async () => "called async",
+                callSync: () => "called sync",
+              },
+            },
+          },
+          jco: {
+            transpile: {
+              extraArgs: {
+                asyncImports: [
+                  "something:test/test-interface#call-async",
+                ],
+                asyncExports: [
+                  "run-async",
+                ],
+              },
+            },
+          },
+        });
+
+        strictEqual(instance.runSync instanceof AsyncFunction, false, "runSync() should be a sync function");
+        strictEqual(instance.runAsync instanceof AsyncFunction, true, "runAsync() should be an async function");
+
+        strictEqual(instance.runSync(), "called sync");
+        strictEqual(await instance.runAsync(), "called async");
+
+        await cleanup();
+      });
+
+      test("Transpile async import and export (NodeJS, JSPI)", async () => {
+        const testMessage = "Hello from Async Function!";
+        const { instance, cleanup, component } = await setupAsyncTest({
+          asyncMode: "jspi",
+          component: {
+            name: "async_call",
+            path: resolve("test/fixtures/components/simple-nested.component.wasm"),
+            imports: {
+              'calvinrp:test-async-funcs/hello': {
+                helloWorld: async () => await Promise.resolve(testMessage),
+              },
+            },
+          },
+          jco: {
+            transpile: {
+              extraArgs: {
+                asyncImports: [
+                  "calvinrp:test-async-funcs/hello#hello-world",
+                ],
+                asyncExports: [
+                  "hello-world",
+                ],
+              },
+            },
+          },
+        });
+
+        strictEqual(instance.hello.helloWorld instanceof AsyncFunction, true, "helloWorld() should be an async function");
+
+        strictEqual(await instance.hello.helloWorld(), testMessage);
+
+        await cleanup();
+      });
+    }
+  });
+}
diff --git a/test/cli.js b/test/cli.js
index 68918b407..cbd0c2834 100644
--- a/test/cli.js
+++ b/test/cli.js
@@ -1,14 +1,7 @@
-import { resolve } from "node:path";
-import { execArgv, env } from "node:process";
+import { resolve, join } from "node:path";
+import { execArgv } from "node:process";
 import { deepStrictEqual, ok, strictEqual } from "node:assert";
-import {
-  mkdir,
-  readdir,
-  readFile,
-  rm,
-  symlink,
-  writeFile,
-} from "node:fs/promises";
+import { mkdir, readFile, rm, symlink, writeFile } from "node:fs/promises";
 
 import { fileURLToPath, pathToFileURL } from "url";
 import { exec, jcoPath, getTmpDir } from "./helpers.js";
@@ -17,6 +10,8 @@ const multiMemory = execArgv.includes("--experimental-wasm-multi-memory")
   ? ["--multi-memory"]
   : [];
 
+const AsyncFunction = (async () => {}).constructor;
+
 export async function cliTest(_fixtures) {
   suite("CLI", () => {
     var tmpDir;
@@ -32,7 +27,7 @@ export async function cliTest(_fixtures) {
       await symlink(
         fileURLToPath(new URL("../packages/preview2-shim", import.meta.url)),
         resolve(modulesDir, "preview2-shim"),
-        "dir"
+        "dir",
       );
     });
     suiteTeardown(async function () {
@@ -55,12 +50,12 @@ export async function cliTest(_fixtures) {
         `test/fixtures/env-allow.composed.wasm`,
         ...multiMemory,
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       await writeFile(
         `${outDir}/package.json`,
-        JSON.stringify({ type: "module" })
+        JSON.stringify({ type: "module" }),
       );
       const m = await import(`${pathToFileURL(outDir)}/env-allow.composed.js`);
       deepStrictEqual(m.testGetEnv(), [["CUSTOM", "VAL"]]);
@@ -73,12 +68,12 @@ export async function cliTest(_fixtures) {
         `test/fixtures/stdio.composed.wasm`,
         ...multiMemory,
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       await writeFile(
         `${outDir}/package.json`,
-        JSON.stringify({ type: "module" })
+        JSON.stringify({ type: "module" }),
       );
       const m = await import(`${pathToFileURL(outDir)}/stdio.composed.js`);
       m.testStdio();
@@ -92,12 +87,12 @@ export async function cliTest(_fixtures) {
         ...multiMemory,
         "--valid-lifting-optimization",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       await writeFile(
         `${outDir}/package.json`,
-        JSON.stringify({ type: "module" })
+        JSON.stringify({ type: "module" }),
       );
       const m = await import(`${pathToFileURL(outDir)}/stdio.composed.js`);
       m.testStdio();
@@ -113,13 +108,51 @@ export async function cliTest(_fixtures) {
         "--name",
         name,
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/${name}.js`);
       ok(source.toString().includes("export { test"));
     });
 
+    if (typeof WebAssembly.Suspending === "function") {
+      test("Transpile with Async Mode for JSPI", async () => {
+        const name = "async_call";
+        const { stderr } = await exec(
+          jcoPath,
+          "transpile",
+          `test/fixtures/components/${name}.component.wasm`,
+          `--name=${name}`,
+          "--valid-lifting-optimization",
+          "--tla-compat",
+          "--instantiation=async",
+          "--base64-cutoff=0",
+          "--async-mode=jspi",
+          "--async-imports=something:test/test-interface#call-async",
+          "--async-exports=run-async",
+          "-o",
+          outDir,
+        );
+        strictEqual(stderr, "");
+        await writeFile(
+          `${outDir}/package.json`,
+          JSON.stringify({ type: "module" }),
+        );
+        const m = await import(`${pathToFileURL(outDir)}/${name}.js`);
+        const inst = await m.instantiate(undefined, {
+          "something:test/test-interface": {
+            callAsync: async () => "called async",
+            callSync: () => "called sync",
+          },
+        });
+        strictEqual(inst.runSync instanceof AsyncFunction, false);
+        strictEqual(inst.runAsync instanceof AsyncFunction, true);
+
+        strictEqual(inst.runSync(), "called sync");
+        strictEqual(await inst.runAsync(), "called async");
+      });
+    }
+
     test("Transpile & Optimize & Minify", async () => {
       const name = "flavorful";
       const { stderr } = await exec(
@@ -134,7 +167,7 @@ export async function cliTest(_fixtures) {
         "--minify",
         "--base64-cutoff=0",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/${name}.js`);
@@ -154,20 +187,20 @@ export async function cliTest(_fixtures) {
         "--tracing",
         "--base64-cutoff=0",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/${name}.js`, "utf8");
       ok(source.includes("function toResultString("));
       ok(
         source.includes(
-          'console.error(`[module="test:flavorful/test", function="f-list-in-record1"] call a'
-        )
+          'console.error(`[module="test:flavorful/test", function="f-list-in-record1"] call a',
+        ),
       );
       ok(
         source.includes(
-          'console.error(`[module="test:flavorful/test", function="list-of-variants"] return result=${toResultString(ret)}`);'
-        )
+          'console.error(`[module="test:flavorful/test", function="list-of-variants"] return result=${toResultString(ret)}`);',
+        ),
       );
     });
 
@@ -179,7 +212,7 @@ export async function cliTest(_fixtures) {
         "--world-name",
         "test:flavorful/flavorful",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/flavorful.d.ts`, "utf8");
@@ -198,10 +231,13 @@ export async function cliTest(_fixtures) {
         "--feature",
         "enable-c",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
-      const source = await readFile(`${outDir}/interfaces/test-feature-gates-unstable-foo.d.ts`, "utf8");
+      const source = await readFile(
+        `${outDir}/interfaces/test-feature-gates-unstable-foo.d.ts`,
+        "utf8",
+      );
       ok(source.includes("export function a(): void;"));
       ok(!source.includes("export function b(): void;"));
       ok(source.includes("export function c(): void;"));
@@ -216,10 +252,13 @@ export async function cliTest(_fixtures) {
         "test:feature-gates-unstable/gated",
         "--all-features",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
-      const source = await readFile(`${outDir}/interfaces/test-feature-gates-unstable-foo.d.ts`, "utf8");
+      const source = await readFile(
+        `${outDir}/interfaces/test-feature-gates-unstable-foo.d.ts`,
+        "utf8",
+      );
       ok(source.includes("export function a(): void;"));
       ok(source.includes("export function b(): void;"));
       ok(source.includes("export function c(): void;"));
@@ -237,10 +276,13 @@ export async function cliTest(_fixtures) {
         "--feature",
         "enable-c",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
-      const source = await readFile(`${outDir}/interfaces/test-feature-gates-unstable-foo.d.ts`, "utf8");
+      const source = await readFile(
+        `${outDir}/interfaces/test-feature-gates-unstable-foo.d.ts`,
+        "utf8",
+      );
       ok(source.includes("export function a(): void;"));
       ok(source.includes("export function b(): void;"));
       ok(source.includes("export function c(): void;"));
@@ -258,6 +300,11 @@ export async function cliTest(_fixtures) {
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/interfaces/test-flavorful-test.d.ts`, "utf8");
+      // NOTE: generation of guest types *no longer* produces an explicitly exported module
+      // but rather contains an typescript ambient module (w/ opt-in for producing explicit
+      // module declarations if necessary)
+      //
+      // see: https://github.com/bytecodealliance/jco/pull/528
       ok(source.includes("declare module 'test:flavorful/test' {"));
     });
 
@@ -268,7 +315,7 @@ export async function cliTest(_fixtures) {
         `test/fixtures/wit/deps/ts-check/ts-check.wit`,
         "--stub",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       {
@@ -278,7 +325,7 @@ export async function cliTest(_fixtures) {
       }
       {
         const source = await readFile(
-          `${outDir}/interfaces/ts-naming-blah.d.ts`
+          `${outDir}/interfaces/ts-naming-blah.d.ts`,
         );
         ok(source.toString().includes("declare function _class(): void"));
         ok(source.toString().includes("export { _class as class }"));
@@ -300,7 +347,7 @@ export async function cliTest(_fixtures) {
         "--js",
         "--base64-cutoff=0",
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/${name}.js`, "utf8");
@@ -320,7 +367,7 @@ export async function cliTest(_fixtures) {
         "--name",
         name,
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/${name}.js`);
@@ -341,7 +388,7 @@ export async function cliTest(_fixtures) {
         "--name",
         name,
         "-o",
-        outDir
+        outDir,
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/${name}.js`);
@@ -354,14 +401,14 @@ export async function cliTest(_fixtures) {
 
     test("Optimize", async () => {
       const component = await readFile(
-        `test/fixtures/components/flavorful.component.wasm`
+        `test/fixtures/components/flavorful.component.wasm`,
       );
       const { stderr, stdout } = await exec(
         jcoPath,
         "opt",
         `test/fixtures/components/flavorful.component.wasm`,
         "-o",
-        outFile
+        outFile,
       );
       strictEqual(stderr, "");
       ok(stdout.includes("Core Module 1:"));
@@ -408,7 +455,7 @@ export async function cliTest(_fixtures) {
       const { stderr, stdout } = await exec(
         jcoPath,
         "print",
-        `test/fixtures/components/flavorful.component.wasm`
+        `test/fixtures/components/flavorful.component.wasm`,
       );
       strictEqual(stderr, "");
       strictEqual(stdout.slice(0, 10), "(component");
@@ -418,7 +465,7 @@ export async function cliTest(_fixtures) {
           "print",
           `test/fixtures/components/flavorful.component.wasm`,
           "-o",
-          outFile
+          outFile,
         );
         strictEqual(stderr, "");
         strictEqual(stdout, "");
@@ -429,7 +476,7 @@ export async function cliTest(_fixtures) {
           "parse",
           outFile,
           "-o",
-          outFile
+          outFile,
         );
         strictEqual(stderr, "");
         strictEqual(stdout, "");
@@ -444,7 +491,7 @@ export async function cliTest(_fixtures) {
         `test/fixtures/wit/deps/app/app.wit`,
         "-o",
         outDir,
-        "--stub"
+        "--stub",
       );
       strictEqual(stderr, "");
       const source = await readFile(`${outDir}/app.js`);
@@ -455,7 +502,7 @@ export async function cliTest(_fixtures) {
       const { stderr, stdout } = await exec(
         jcoPath,
         "wit",
-        `test/fixtures/components/flavorful.component.wasm`
+        `test/fixtures/components/flavorful.component.wasm`,
       );
       strictEqual(stderr, "");
       ok(stdout.includes("world root {"));
@@ -472,7 +519,7 @@ export async function cliTest(_fixtures) {
           "-m",
           "processed-by=dummy-gen@test",
           "-o",
-          outFile
+          outFile,
         );
         strictEqual(stderr, "");
         strictEqual(stdout, "");
@@ -489,7 +536,7 @@ export async function cliTest(_fixtures) {
           "new",
           outFile,
           "-o",
-          outFile
+          outFile,
         );
         strictEqual(stderr, "");
         strictEqual(stdout, "");
@@ -504,10 +551,17 @@ export async function cliTest(_fixtures) {
           jcoPath,
           "metadata-show",
           outFile,
-          "--json"
+          "--json",
         );
         strictEqual(stderr, "");
         const meta = JSON.parse(stdout);
+        // NOTE: the check below is depends on *how many* modules *and* components are
+        // generated by wit-component (as used by the wasm-tools rust dep in this project)
+        // and componentize-js.
+        //
+        // As such, this is subject to optimizations or changes in operation of
+        // upstream functionality and may change with upstream releases -- for example
+        // the addition of a "glue" or redirection-heavy module/component
         deepStrictEqual(meta[0].metaType, { tag: "component", val: 5 });
         deepStrictEqual(meta[1].producers, [
           [
@@ -529,7 +583,7 @@ export async function cliTest(_fixtures) {
         "test/fixtures/modules/exitcode.wasm",
         "--wasi-reactor",
         "-o",
-        outFile
+        outFile,
       );
       strictEqual(stderr, "");
       {
@@ -544,7 +598,7 @@ export async function cliTest(_fixtures) {
         jcoPath,
         "metadata-show",
         "test/fixtures/modules/exitcode.wasm",
-        "--json"
+        "--json",
       );
       strictEqual(stderr, "");
       deepStrictEqual(JSON.parse(stdout), [
@@ -557,7 +611,7 @@ export async function cliTest(_fixtures) {
     });
 
     test("Componentize", async () => {
-      const args = [
+      const { stdout, stderr } = await exec(
         jcoPath,
         "componentize",
         "test/fixtures/componentize/source.js",
@@ -567,13 +621,8 @@ export async function cliTest(_fixtures) {
         "-w",
         "test/fixtures/componentize/source.wit",
         "-o",
-        outFile
-      ];
-      if (env.WEVAL_BIN_PATH) {
-        args.push("--weval-bin", env.WEVAL_BIN_PATH);
-      }
-
-      const { stdout, stderr } = await exec(...args);
+        outFile,
+      );
       strictEqual(stderr, "");
       {
         const { stderr } = await exec(
@@ -585,13 +634,13 @@ export async function cliTest(_fixtures) {
           "--map",
           "local:test/foo=./foo.js",
           "-o",
-          outDir
+          outDir,
         );
         strictEqual(stderr, "");
       }
       await writeFile(
         `${outDir}/package.json`,
-        JSON.stringify({ type: "module" })
+        JSON.stringify({ type: "module" }),
       );
       await writeFile(`${outDir}/foo.js`, `export class Bar {}`);
       const m = await import(`${pathToFileURL(outDir)}/componentize.js`);
@@ -600,3 +649,32 @@ export async function cliTest(_fixtures) {
     });
   });
 }
+
+// Cache of componentize byte outputs
+const CACHE_COMPONENTIZE_OUTPUT = {};
+
+/**
+ * Small cache for componentizations to save build time by storing componentize
+ * output in memory
+ *
+ * @param {string} outputPath - path to where to write the component
+ * @param {string[]} args - arguments to be fed to `jco componentize` (*without* "compnentize" or "-o/--output")
+ */
+async function cachedComponentize(outputPath, args) {
+  const cacheKey = args.join("+");
+  if (cacheKey in CACHE_COMPONENTIZE_OUTPUT) {
+    await writeFile(outputPath, CACHE_COMPONENTIZE_OUTPUT[cacheKey]);
+    return;
+  }
+
+  const { stdout, stderr } = await exec(
+    jcoPath,
+    "componentize",
+    ...args,
+    "-o",
+    outputPath,
+  );
+  strictEqual(stderr, "");
+
+  CACHE_COMPONENTIZE_OUTPUT[cacheKey] = await readFile(outputPath);
+}
diff --git a/test/fixtures/browser/test-pages/something__test.async.html b/test/fixtures/browser/test-pages/something__test.async.html
new file mode 100644
index 000000000..6da546a3d
--- /dev/null
+++ b/test/fixtures/browser/test-pages/something__test.async.html
@@ -0,0 +1,100 @@
+<!DOCTYPE html>
+<!--
+
+This page tests a component with the following WIT interface:
+
+```
+package something:test;
+
+interface test-interface {
+  call-async: func() -> string;
+  call-sync: func() -> string;
+}
+
+world component {
+  import test-interface;
+
+  export run-async: func() -> string;
+  export run-sync: func() -> string;
+}
+```
+
+The component must be transpiled with async enabled, and is loaded by this page,
+then executed by the browser with an async function.
+-->
+<!-- The script below loads and instantiates the module -->
+<script type="module">
+ // OK/Error states for the test function
+ // (the test harness should check for body contents)
+ function ok(msg) { document.body.innerHTML = typeof msg === "object" ? JSON.stringify(msg) : `${err}`; }
+ function err(err) { document.body.innerHTML = typeof err === "object" ? JSON.stringify(err) : `${err}`; }
+
+ // Prefix used in URL hash to direct the backend test server to serve up
+ // a specific (transpiled) JS lib
+ const HASH_PREFIX_DYNAMIC_COMPONENT = 'transpiled:'
+
+ ok({ responseText: "after hash" });
+
+ const testName = window.location.hash.slice(1);
+ document.body.innerHTML = '<h1>Running</h1>';
+
+ if (testName.startsWith(HASH_PREFIX_DYNAMIC_COMPONENT)) {
+   // We expect to be called with a hash prefix noting the path to the component we should load
+   await runTranspiledModuleTest(testName.slice(HASH_PREFIX_DYNAMIC_COMPONENT.length));
+ } else {
+   err(`Unknown test case "${testName}"`);
+ }
+
+ async function runTranspiledModuleTest(moduleName) {
+   // Run tests on components in the tmpdir directory (as reflected by the backing web server)
+   const testModule = `/transpiled/${moduleName}`;
+   try {
+     /* Load the module */
+     const mod = await import(testModule);
+
+     // Instantiate the module, with the WASI browser shim
+     let instantiated;
+     try {
+       instantiated = await mod.instantiate(undefined, {
+         "something:test/test-interface": {
+           callAsync: async () => {
+             return new Promise(resolve => setTimeout(resolve("callAsync"), 2000));
+           },
+           callSync: () => {
+             return "callSync";
+           }
+         },
+       });
+     } catch (e) {
+       err(`ERROR while instantiating [${testModule}]:\n\n${e}\n${e.stack}`);
+       return;
+     }
+
+     // Ensure the module conforms to `wasi:http/incoming-handler#handle`, or at least has a `handle` function
+     const fn = instantiated?.runAsync;
+     if (!fn) {
+       throw new Error(`Expected test module "${testModule}" to export a "runAsync" function. It only contains keys [${Object.keys(instantiated)}]`);
+     }
+
+     // Before running the function, we start off a separate task that will count every 50ms
+     // which we expect to run (without being blocked on WebAssembly)
+     let count = 0;
+     const wake = setInterval(() => {
+       count += 1;
+     }, 50);
+
+     // Run the exported function (which will call the async host import above),
+     // get response
+     const responseText = await fn();
+
+     if (count <= 20) {
+       err(`ERROR setTimeout did not run unimpeded, only completed [${count}] 50ms increments (expected ~20)`);
+     }
+
+     ok({ responseText });
+   } catch (e) {
+     err(`ERROR while running [${testModule}]:\n\n${e}\n${e.stack}`);
+   }
+ }
+
+</script>
diff --git a/test/fixtures/components/async_call.component.wasm b/test/fixtures/components/async_call.component.wasm
new file mode 100644
index 000000000..a52483904
Binary files /dev/null and b/test/fixtures/components/async_call.component.wasm differ
diff --git a/test/helpers.js b/test/helpers.js
index c3236fba4..f4007a7e7 100644
--- a/test/helpers.js
+++ b/test/helpers.js
@@ -1,11 +1,62 @@
-import { tmpdir } from "node:os";
+import { version, env, argv, execArgv } from "node:process";
+import { createServer as createNetServer } from "node:net";
+import { createServer as createHttpServer } from "node:http";
+import {
+  basename,
+  join,
+  isAbsolute,
+  resolve,
+  normalize,
+  sep,
+  relative,
+  dirname,
+  extname,
+} from "node:path";
+import {
+  cp,
+  mkdtemp,
+  writeFile,
+  stat,
+  mkdir,
+  readFile,
+} from "node:fs/promises";
+import { ok, strictEqual } from "node:assert";
 import { spawn } from "node:child_process";
-import { argv, execArgv } from "node:process";
-import { normalize, sep } from "node:path";
-import { mkdtemp } from "node:fs/promises";
+import { tmpdir } from "node:os";
+
+import mime from "mime";
+import { pathToFileURL } from "url";
 
+import { transpile } from "../src/api.js";
+import { componentize } from "../src/cmd/componentize.js";
+
+// Path to the jco binary
 export const jcoPath = "src/jco.js";
 
+// Simple debug logging for tests
+export function log(args, ..._rest) {
+  if (!env.TEST_DEBUG) {
+    return;
+  }
+  if (typeof args === "string") {
+    args = { msg: args };
+  }
+  if (typeof args !== "object") {
+    return;
+  }
+  if (args.extra || _rest.length > 0) {
+    console.log(`[${args.level || "debug"}] ${args.msg}`, {
+      ...args.extra,
+      _rest,
+    });
+  } else {
+    console.log(`[${args.level || "debug"}] ${args.msg}`);
+  }
+}
+
+// Execute a NodeJS script
+//
+// Note: argv[0] is expected to be `node` (or some incantation that spawned this process)
 export async function exec(cmd, ...args) {
   let stdout = "",
     stderr = "";
@@ -44,3 +95,455 @@ export async function exec(cmd, ...args) {
 export async function getTmpDir() {
   return await mkdtemp(normalize(tmpdir() + sep));
 }
+
+/**
+ * Set up an async test to be run
+ *
+ * @param {object} args - Arguments for running the async test
+ * @param {function} args.testFn - Arguments for running the async test
+ * @param {object} args.jco - JCO-related confguration for running the async test
+ * @param {string} [args.jcoBinPath] - path to the jco binary (or a JS script)
+ * @param {object} [args.transpile] - configuration related to transpilation
+ * @param {string[]} [args.transpile.extraArgs] - arguments to pass along to jco transpilation
+ * @param {object} args.component - configuration for an existing component that should be transpiled
+ * @param {string} args.component.name - name of the component
+ * @param {string} args.component.path - path to the WebAssembly binary for the existing component
+ * @param {object[]} args.component.import - imports that should be provided to the module at instantiation time
+ * @param {object} args.component.build - configuration for building an ephemeral component to be tested
+ * @param {object} args.component.js.source - Javascript source code for a component
+ * @param {object} args.component.wit.source - WIT definitions (inlined) for a component
+ * @param {object[]} args.component.wit.deps - Dependencies (ex. WASI) that should be included during component build
+ */
+export async function setupAsyncTest(args) {
+  const { asyncMode, testFn, jco, component } = args;
+  const jcoBinPath = jco?.binPath || jcoPath;
+
+  let componentName = component.name;
+  let componentPath = component.path;
+  let componentImports = component.imports;
+
+  if (component.path && component.build) {
+    throw new Error(
+      "Both component.path and component.build should not be specified at the same time",
+    );
+  }
+
+  // If this component should be built "just in time" -- i.e. created when this test is run
+  let componentBuildCleanup;
+  if (component.build) {
+    // Optionally use a custom pre-optimized StarlingMonkey engine
+    if (env.TEST_CUSTOM_ENGINE_JIT_PATH || env.TEST_CUSTOM_ENGINE_AOT_PATH) {
+      log("detected custom engine JIT path");
+      if (component.build.componentizeOpts?.aot) {
+        log("detected AOT config");
+        component.build.engine = env.TEST_CUSTOM_ENGINE_AOT_PATH;
+      } else {
+        log("detected JIT config");
+        component.build.engine = env.TEST_CUSTOM_ENGINE_JIT_PATH;
+      }
+    }
+
+    // Build the component
+    const { name, path, cleanup } = await buildComponent({
+      name: componentName,
+      ...component.build,
+    });
+
+    componentBuildCleanup = cleanup;
+    componentName = name;
+    componentPath = path;
+  }
+
+  if (!componentName) {
+    throw new Error("invalid/missing component name");
+  }
+  if (!componentPath) {
+    throw new Error("invalid/missing component path");
+  }
+
+  // Use either a temporary directory or an subfolder in an existing directory,
+  // creating it if it doesn't already exist
+  const outputDir = component.outputDir
+    ? component.outputDir
+    : await getTmpDir();
+
+  // Build out the whole-test cleanup function
+  let cleanup = async () => {
+    log("[cleanup] cleaning up component...");
+    if (componentBuildCleanup) {
+      try {
+        await componentBuildCleanup();
+      } catch {}
+    }
+    try {
+      await rm(outputDir, { recursive: true });
+    } catch {}
+  };
+
+  // Return early if the test was intended to run on JSPI but JSPI is not enabled
+  if (asyncMode == "jspi" && typeof WebAssembly?.Suspending !== "function") {
+    let nodeMajorVersion = parseInt(version.replace("v","").split(".")[0]);
+    if (nodeMajorVersion < 23) {
+      throw new Error("NodeJS versions <23 does not support JSPI integration, please use a NodeJS version >=23");
+    }
+    await cleanup();
+    throw new Error(
+      "JSPI async type skipped, but JSPI was not enabled -- please ensure test is run from an environment with JSPI integration (ex. node with the --experimental-wasm-jspi flag)",
+    );
+  }
+
+  // Build a directory for the transpiled component output to be put in
+  // (possibly inside the passed in outputDir)
+  const moduleOutputDir = join(outputDir, component.name);
+  try {
+    await stat(moduleOutputDir);
+  } catch (err) {
+    if (err && err.code && err.code === "ENOENT") {
+      await mkdir(moduleOutputDir);
+    }
+  }
+
+  const transpileOpts = {
+    name: componentName,
+    minify: true,
+    validLiftingOptimization: true,
+    tlaCompat: true,
+    optimize: false,
+    base64Cutoff: 0,
+    instantiation: "async",
+    asyncMode,
+    wasiShim: true,
+    outDir: moduleOutputDir,
+    ...(jco?.transpile?.extraArgs || {}),
+  };
+
+  const componentBytes = await readFile(componentPath);
+
+  // Perform transpilation, write out files
+  const { files } = await transpile(componentBytes, transpileOpts);
+  await Promise.all(
+    Object.entries(files).map(async ([name, file]) => {
+      await mkdir(dirname(name), { recursive: true });
+      await writeFile(name, file);
+    }),
+  );
+
+  // Write a minimal package.json
+  await writeFile(
+    `${moduleOutputDir}/package.json`,
+    JSON.stringify({ type: "module" }),
+  );
+
+  // TODO: DEBUG module import not working, file is missing!
+  // log("WROTE EVERYTHING:", moduleOutputDir);
+  // await new Promise(resolve => setTimeout(resolve, 60_000));
+
+  // Import the transpiled JS
+  const esModuleOutputPath = join(moduleOutputDir, `${componentName}.js`);
+  const esModuleSourcePathURL = pathToFileURL(esModuleOutputPath);
+  const module = await import(esModuleSourcePathURL);
+
+  // TODO: DEBUG module import not working, file is missing!
+  // log("PRE INSTANTIATION", { moduleOutputDir });
+  // await new Promise(resolve => setTimeout(resolve, 60_000_000));
+
+  // Optionally instantiate the module
+  //
+  // It's useful to be able to skip instantiation of the instantiation should happen
+  // elsewhere (ex. in a browser window)
+  let instance = null;
+  if (!component.skipInstantiation) {
+    instance = await module.instantiate(undefined, componentImports || {});
+  }
+
+  return {
+    module,
+    esModuleOutputPath,
+    esModuleSourcePathURL,
+    esModuleRelativeSourcePath: relative(outputDir, esModuleOutputPath),
+    instance,
+    cleanup,
+    outputDir,
+    component: {
+      name: componentName,
+      path: componentPath,
+    },
+  };
+}
+
+/**
+ * Helper method for building a component just in time (e.g. to use in a test)
+ *
+ */
+export async function buildComponent(args) {
+  if (!args) {
+    throw new Error("missing args");
+  }
+  const name = args.name;
+  const jsSource = args.js?.source;
+  const witDeps = args.wit?.deps;
+  const witSource = args.wit?.source;
+  const witWorld = args.wit?.world;
+  if (!name) {
+    throw new Error(
+      "invalid/missing component name for in-test component build",
+    );
+  }
+  if (!jsSource) {
+    throw new Error("invalid/missing source for in-test component build");
+  }
+  if (!witSource) {
+    throw new Error("invalid/missing WIT for in-test component build");
+  }
+  if (!witWorld) {
+    throw new Error("invalid/missing WIT world for in-test component build");
+  }
+
+  // Create temporary output directory
+  const outputDir = await getTmpDir();
+
+  // Write the component's JS and WIT
+  const jsSourcePath = join(outputDir, "component.js");
+  const witOutputPath = join(outputDir, "wit");
+  await mkdir(join(witOutputPath, "deps"), { recursive: true });
+  const witSourcePath = join(witOutputPath, "component.wit");
+
+  // Write the appropriate
+  await Promise.all([
+    await writeFile(jsSourcePath, jsSource),
+    await writeFile(witSourcePath, witSource),
+  ]);
+
+  // Copy in additional WIT dependency files if provided
+  if (witDeps) {
+    for (const dep of witDeps) {
+      if (!dep.srcPath) {
+        throw new Error("Invalid wit dep object, missing srcPath");
+      }
+      if (!isAbsolute(dep.srcPath)) {
+        throw new Error("Only absolute source paths are allowed");
+      }
+      if (dep.destPath && isAbsolute(dep.destPath)) {
+        throw new Error(
+          "Only relative dest paths are allowed (into the wit/deps directory)",
+        );
+      }
+
+      const srcFileStats = await stat(dep.srcPath);
+      const destPath =
+        dep.destPath || (srcFileStats.isFile() ? basename(dep.srcPath) : ".");
+      const outputPath = resolve(`${outputDir}/wit/deps/${destPath}`);
+
+      if (srcFileStats.isFile()) {
+        await writeFile(outputPath, await readFile(dep.srcPath));
+      } else if (srcFileStats.isDirectory()) {
+        await cp(dep.srcPath, outputPath, { recursive: true });
+      } else {
+        throw new Error(
+          "unrecognized file type for WIT dep, neither file nor directory",
+        );
+      }
+    }
+  }
+
+  // Build the output path to which we should write
+  const outputWasmPath = join(outputDir, "component.wasm");
+
+  // Build options for componentizing
+  const wit = witDeps ? witOutputPath : witSourcePath;
+  const options = {
+    sourceName: "component",
+    // If there were wit deps specified, we should use the whole wit dir
+    // otherwise we can use just the single WIT source file
+    wit,
+    worldName: witWorld,
+    out: outputWasmPath,
+    quiet: true,
+    // Add in optional raw options object to componentize
+    ...(args.componentizeOpts || {}),
+  };
+
+  // Use a custom engine if specified
+  if (args.engine) {
+    const enginePath = resolve(args.engine);
+    const engine = await stat(enginePath);
+    if (engine.isFile()) {
+      options.engine = enginePath;
+    }
+  }
+
+  // Perform componentization
+  await componentize(jsSourcePath, options);
+
+  return {
+    name,
+    path: outputWasmPath,
+    cleanup: async () => {
+      try {
+        await rm(outputDir);
+      } catch {}
+    },
+  };
+}
+
+/**
+ * Load a browser page, usually triggering test output that is written
+ * to the HTML body of the page
+ *
+ * @param {object} args
+ * @param {object} args.browser - Puppeteer browser instance
+ * @param {object} [args.path] - Path to the HTML file to use, with root at `test` (ex. `test/browser.html` would be just `browser.html`)
+ * @param {string} args.hash - Hash at which to perform tests (used to identify specific tests)
+ */
+export async function loadTestPage(args) {
+  const { browser, hash } = args;
+  if (!browser) {
+    throw new Error("missing puppeteer instance browser object");
+  }
+  if (!hash) {
+    throw new Error("missing hash for browser page");
+  }
+
+  const page = await browser.newPage();
+
+  // Pass along all output to test
+  if (env.TEST_DEBUG) {
+    page
+      .on("console", (message) =>
+        log(
+          `[browser] ${message.type().substr(0, 3).toUpperCase()} ${message.text()}`,
+        ),
+      )
+      .on("pageerror", ({ message }) => log(`[browser] ${message}`))
+      .on("response", (response) =>
+        log(`[browser] ${response.status()} ${response.url()}`),
+      )
+      .on("requestfailed", (request) =>
+        log(`[browser] ${request.failure().errorText} ${request.url()}`),
+      );
+  }
+
+  const path = args.path ? args.path : "test/browser.html";
+  const serverPort = args.serverPort ? args.serverPort : 8080;
+
+  const hashURL = `http://localhost:${serverPort}/${path}#${hash}`;
+  log(`[browser] attempting to navigate to [${hashURL}]`);
+  const hashTest = await page.goto(hashURL);
+  ok(hashTest.ok(), `navigated to URL [${hashURL}]`);
+
+  const body = await page.locator("body").waitHandle();
+
+  let bodyHTML = await body.evaluate((el) => el.innerHTML);
+  // If the body HTML uses "Running" to show state, wait until it changes
+  if (bodyHTML == "<h1>Running</h1>") {
+    while (bodyHTML === "<h1>Running</h1>") {
+      bodyHTML = await body.evaluate((el) => el.innerHTML);
+    }
+  }
+
+  // Attempt to parse the HTML body content as JSON
+  const raw = bodyHTML;
+  let testOutputJSON;
+  try {
+    testOutputJSON = JSON.parse(raw);
+  } catch (err) {
+    log(`failed to parse JSON for body HTML: ${err}`);
+  }
+
+  return {
+    page,
+    body,
+    output: {
+      raw,
+      json: testOutputJSON,
+    },
+  };
+}
+
+// Utility function for getting a random port
+export async function getRandomPort() {
+  return await new Promise((resolve) => {
+    const server = createNetServer();
+    server.listen(0, function () {
+      const port = this.address().port;
+      server.on("close", () => resolve(port));
+      server.close();
+    });
+  });
+}
+
+/**
+ * Start a web server that serves components and related files from a
+ * given directory.
+ *
+ * @param {{ servePaths: { basePath: string, urlPrefix: string }[] }} args
+ * @returns {Promise<{ serverPort: number, server: object }>}
+ */
+export async function startTestWebServer(args) {
+  if (!args.routes) { throw new Error("missing serve paths"); }
+  const serverPort = await getRandomPort();
+
+  const server = createHttpServer(async (req, res) => {
+    // Build a utility fucntion for returning an error
+    const returnError = (e) => {
+      log(`[webserver] failed to find file [${fileURL}]`);
+      res.writeHead(404);
+      res.end(e.message);
+    };
+
+    // Find route to serve incoming request
+    const route = args.routes.find(dir => {
+      return !dir.urlPrefix || (dir.urlPrefix && req.url.startsWith(dir.urlPrefix));
+    });
+    if (!route) {
+      log(`[webserver] failed to find route to serve [${req.url.path}]`);
+      returnError(new Error(`failed to resolve url [${req.url}] with any provided routes`));
+      return;
+    }
+    if (!route.basePathURL) { throw new Error("invalid/missing path in specified route"); }
+
+    const fileURL = new URL(
+      `./${req.url.slice(route.urlPrefix ? route.urlPrefix.length : "")}`,
+      route.basePathURL,
+    );
+
+    log(`[webserver] attempting to read file on disk @ [${fileURL}]`);
+
+    // Attempt to read the file
+    try {
+      const html = await readFile(fileURL);
+      res.writeHead(200, {
+        "content-type": mime.getType(extname(req.url)),
+      });
+      res.end(html);
+      log(`[webserver] served file [${fileURL}]`);
+    } catch (e) {
+      if (e.code === "ENOENT") {
+        returnError(e);
+      } else {
+        log(`[webserver] ERROR [${e}]`);
+        res.writeHead(500);
+        res.end(e.message);
+      }
+    }
+  });
+
+  const served = new Promise(resolve => {
+    server.on('listening', () => {
+      resolve({
+        serverPort,
+        server,
+        cleanup: async () => {
+          log("[cleanup] cleaning up http server...");
+          server.close(() => {
+            log("server successfully closed");
+          });
+        }
+      });
+    });
+  });
+
+  server.listen(serverPort);
+
+  return await served;
+}
diff --git a/test/test.js b/test/test.js
index b08589014..79a275a63 100644
--- a/test/test.js
+++ b/test/test.js
@@ -25,6 +25,8 @@ const componentFixtures = env.COMPONENT_FIXTURES
       )
       .map((f) => f.name);
 
+import { asyncBrowserTest } from './async.browser.js';
+import { asyncTest } from './async.js';
 import { browserTest } from './browser.js';
 import { codegenTest } from './codegen.js';
 import { runtimeTest } from './runtime.js';
@@ -43,6 +45,8 @@ await commandsTest();
 await apiTest(componentFixtures);
 await cliTest(componentFixtures);
 await witTest();
+await asyncTest();
+await asyncBrowserTest();
 
 if (platform !== 'win32')
   await browserTest();
diff --git a/xtask/src/build/jco.rs b/xtask/src/build/jco.rs
index cdd53437e..bae63ac37 100644
--- a/xtask/src/build/jco.rs
+++ b/xtask/src/build/jco.rs
@@ -85,6 +85,7 @@ fn transpile(component_path: &str, name: String, optimize: bool) -> Result<()> {
         multi_memory: true,
         import_bindings: Some(BindingsMode::Js),
         guest: false,
+        async_mode: None,
     };
 
     let transpiled = js_component_bindgen::transpile(&adapted_component, opts)?;
diff --git a/xtask/src/generate/wasi_types.rs b/xtask/src/generate/wasi_types.rs
index 12b34fa28..ab170d640 100644
--- a/xtask/src/generate/wasi_types.rs
+++ b/xtask/src/generate/wasi_types.rs
@@ -39,6 +39,7 @@ pub(crate) fn run() -> Result<()> {
             multi_memory: false,
             import_bindings: Some(BindingsMode::Js),
             guest: false,
+            async_mode: None,
         };
 
         let files = generate_types(name, resolve, world, opts)?;