diff --git a/stubs/machine.c b/stubs/machine.c
index aafb0ec..e73f644 100644
--- a/stubs/machine.c
+++ b/stubs/machine.c
@@ -22,6 +22,10 @@ static void init_asyncify_buf(struct asyncify_buf *buf)
 
 static void *_asyncjmp_active_scan_buf = NULL;
 
+// Separate buffer for async web API operations (isolated from setjmp)
+static struct asyncify_buf _async_web_api_buf;
+static int _async_web_api_in_unwind = 0;
+
 void asyncjmp_scan_locals(asyncjmp_scan_func scan)
 {
     static struct asyncify_buf buf;
@@ -42,6 +46,33 @@ void asyncjmp_scan_locals(asyncjmp_scan_func scan)
     }
 }
 
+// Start async web API unwind - saves setjmp state if active
+void async_web_api_unwind(void)
+{
+    if (!_async_web_api_in_unwind)
+    {
+        _async_web_api_in_unwind = 1;
+        init_asyncify_buf(&_async_web_api_buf);
+        asyncify_start_unwind(&_async_web_api_buf);
+    }
+}
+
+// Stop async web API unwind and restore setjmp context
+void async_web_api_stop(void)
+{
+    if (_async_web_api_in_unwind)
+    {
+        asyncify_stop_rewind();
+        _async_web_api_in_unwind = 0;
+    }
+}
+
+// Handle async web API unwind - called from runtime.c
+void *async_web_api_handle_unwind(void)
+{
+    return (_async_web_api_in_unwind) ? &_async_web_api_buf : NULL;
+}
+
 static void *asyncjmp_stack_base = NULL;
 
 __attribute__((constructor)) int asyncjmp_record_stack_base(void)
diff --git a/stubs/machine.h b/stubs/machine.h
index d4fcc9c..576cfb5 100644
--- a/stubs/machine.h
+++ b/stubs/machine.h
@@ -21,4 +21,13 @@ void asyncjmp_set_stack_pointer(void *sp);
 // Used by the top level Asyncify handling in wasm/runtime.c
 void *asyncjmp_handle_scan_unwind(void);
 
+// Start async web API unwind - uses separate buffer from setjmp
+void async_web_api_unwind(void);
+
+// Stop async web API unwind
+void async_web_api_stop(void);
+
+// Handle async web API unwind
+void *async_web_api_handle_unwind(void);
+
 #endif
\ No newline at end of file
diff --git a/stubs/runtime.c b/stubs/runtime.c
index b1a0f7d..b5506e4 100644
--- a/stubs/runtime.c
+++ b/stubs/runtime.c
@@ -34,6 +34,12 @@ int asyncjmp_rt_start(int(main)(int argc, char **argv), int argc, char **argv)
             asyncify_start_rewind(asyncify_buf);
             continue;
         }
+        // Handle async web API unwind - uses separate buffer from setjmp
+        if ((asyncify_buf = async_web_api_handle_unwind()) != NULL)
+        {
+            asyncify_start_rewind(asyncify_buf);
+            continue;
+        }
 
         break;
     }