In May 2024, the Flutter team stabilized WebAssembly support by integrating the Dart compiler with WASM GC. Since late 2024, Dart DevTools has used WebAssembly by default. However, Flutter/WASM is not yet officially supported across all browsers, and the framework automatically switches to a JavaScript fallback if it detects incompatibility.
Firefox supports WasmGC since version 120, but Flutter disables this mode due to a rendering issue with Skwasm. Firefox performs expensive CPU-based copying when transferring images from OffscreenCanvas, taking 25–30 ms compared to 0–0.1 ms in Chrome. Mozilla bug #1788206 remains open with no assigned developer.
In Safari, while version 18.2 added WasmGC support and a critical crash was resolved, official Flutter/WASM support remains disabled. In August 2026, the Flutter team closed a PR that would have enabled WASM for Safari 26, opting instead to implement a compatibility check. WebKit still faces performance issues with Canvas/ImageBitmap transfers.
Currently, Flutter/WASM is not officially functional in Safari, Chrome, Firefox, or Edge on iOS, as all iOS browsers rely on WebKit. Developers can use the --wasm flag for production, which ensures Chromium browsers use WASM while others default to the JavaScript version. The Flutter issue #178893 regarding full WASM enablement remains open.
