# Swift for WebAssembly **URL:** https://forums.swift.org/c/platform/swift-for-webassembly/71.md [Latest](https://forums.swift.org/latest.md) · [Categories](https://forums.swift.org/categories.md) · [Tags](https://forums.swift.org/tags.md) --- ## [About the Swift for WebAssembly category](https://forums.swift.org/t/about-the-swift-for-webassembly-category/44721)
**Author:** [@mishal\_shah](https://forums.swift.org/u/mishal_shah)\ **Replies:** 3\ **Last updated:** [February 28, 2021, 4:18pm UTC](https://forums.swift.org/t/about-the-swift-for-webassembly-category/44721 "2021-02-28T16:18:40Z")
Discussions about WebAssembly support in the Swift toolchain and libraries targeting this platform. --- ## [Swift for Wasm September 2026 Updates](https://forums.swift.org/t/swift-for-wasm-september-2026-updates/89836)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [September 30, 2026, 3:22pm UTC](https://forums.swift.org/t/swift-for-wasm-september-2026-updates/89836 "2026-09-30T15:22:38Z")
Notable changes this month: WasmKit 0.4.0 made its interpreter about twice as fast and runs on microcontrollers, and 0.4.1 added the typed function references proposal; JavaScriptKit 0.59.0 can generate packages running … --- ## [What happened to \`wasm32-unknown-wasip1-threads\`?](https://forums.swift.org/t/what-happened-to-wasm32-unknown-wasip1-threads/85656)
**Author:** [@taylorswift](https://forums.swift.org/u/taylorswift)\ **Replies:** 7\ **Last updated:** [September 29, 2026, 2:28pm UTC](https://forums.swift.org/t/what-happened-to-wasm32-unknown-wasip1-threads/85656 "2026-09-29T14:28:12Z")
the most recent 6.3 development snapshot (Release swift-wasm-6.3-SNAPSHOT-2026-03-05-a · swiftwasm/swift · GitHub) had a wasm32-unknown-wasip1-threads bundle. but there is no corresponding swift-6.3-RELEASE bundle on tha… --- ## [WasmKit 0.4.0 - 2x Faster, and Running on Microcontrollers](https://forums.swift.org/t/wasmkit-0-4-0-2x-faster-and-running-on-microcontrollers/89665)
**Author:** [@kateinoigakukun](https://forums.swift.org/u/kateinoigakukun)\ **Replies:** 0\ **Last updated:** [September 19, 2026, 11:05am UTC](https://forums.swift.org/t/wasmkit-0-4-0-2x-faster-and-running-on-microcontrollers/89665 "2026-09-19T11:05:19Z")
WasmKit 0.4.0 is now available. This release is mostly about three things: The interpreter got roughly twice as fast The engine and its GDB stub now run on microcontrollers via Embedded Swift support Support for a few… --- ## [Swift for Wasm August 2026 Updates](https://forums.swift.org/t/swift-for-wasm-august-2026-updates/89316)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [September 1, 2026, 3:24pm UTC](https://forums.swift.org/t/swift-for-wasm-august-2026-updates/89316 "2026-09-01T15:24:50Z")
Notable changes this month: WasmKit now runs both a WASI guest and its GDB stub on an ESP32; BridgeJS gained imports from external ECMAScript modules, generic imported functions, and JS-side export renaming across JavaSc… --- ## [Swift for Wasm July 2026 Updates](https://forums.swift.org/t/swift-for-wasm-july-2026-updates/88673)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [July 31, 2026, 12:09pm UTC](https://forums.swift.org/t/swift-for-wasm-july-2026-updates/88673 "2026-07-31T12:09:17Z")
Notable changes this month: work on an Emscripten-hosted Swift toolchain; IRGen gained a fix for async typed throws miscompiles on wasm32; WasmKit implemented the Relaxed SIMD and extended-const proposals along with shar… --- ## [How to use compile code with the newest Swift Embedded features in Swift WASM](https://forums.swift.org/t/how-to-use-compile-code-with-the-newest-swift-embedded-features-in-swift-wasm/88438)
**Author:** [@vitamin](https://forums.swift.org/u/vitamin)\ **Replies:** 0\ **Last updated:** [July 21, 2026, 6:25pm UTC](https://forums.swift.org/t/how-to-use-compile-code-with-the-newest-swift-embedded-features-in-swift-wasm/88438 "2026-07-21T18:25:38Z")
As of mid-July 2026, the Embedded Swift documentation about existentials says: • Embedded Swift allows and supports forming existentials of any kind • Existentials in Embedded Swift allow the “is” and “as!” / “as?” op… --- ## [WASM-optimized JSON-parsing library (no Foundation)](https://forums.swift.org/t/wasm-optimized-json-parsing-library-no-foundation/88365)
**Author:** [@vitamin](https://forums.swift.org/u/vitamin)\ **Replies:** 0\ **Last updated:** [July 18, 2026, 4:49pm UTC](https://forums.swift.org/t/wasm-optimized-json-parsing-library-no-foundation/88365 "2026-07-18T16:49:18Z")
.o size: 154 kb .a size: 360 kb 1.4x faster than Foundation parser 169mb/s serialization in my testing Base lib supports Embedded Swift as of FTT version 2.0.0 Size with Codable support added is +56kb/+275kb (Codabl… --- ## [Swift for Wasm June 2026 Updates](https://forums.swift.org/t/swift-for-wasm-june-2026-updates/87820)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [June 29, 2026, 1:19pm UTC](https://forums.swift.org/t/swift-for-wasm-june-2026-updates/87820 "2026-06-29T13:19:17Z")
Notable changes this month: the Swift.org blog covered how Goodnotes shipped its app to the web with Swift and WebAssembly; Emscripten support improved in the Swift compiler, the standard library, and the test suite; Jav… --- ## [A Swift wasm WebGPU State Machine Engine](https://forums.swift.org/t/a-swift-wasm-webgpu-state-machine-engine/87289)
**Author:** [@vitamin](https://forums.swift.org/u/vitamin)\ **Replies:** 1\ **Last updated:** [June 12, 2026, 11:45pm UTC](https://forums.swift.org/t/a-swift-wasm-webgpu-state-machine-engine/87289 "2026-06-12T23:45:12Z")
Check out our SwiftXState wasm WebGPU proof of concept Direct link to WebGPU demo: SwiftXState/Examples/WasmGPUDemo at main · gistya/SwiftXState · GitHub It's still very early stages for the library but it was prett… --- ## [Swift for Wasm May 2026 Updates](https://forums.swift.org/t/swift-for-wasm-may-2026-updates/86981)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 1\ **Last updated:** [June 2, 2026, 10:34am UTC](https://forums.swift.org/t/swift-for-wasm-may-2026-updates/86981 "2026-06-02T10:34:11Z")
Notable changes this month: JavaScriptKit 0.52.0-0.53.0 with continued BridgeJS improvements for compatibility and performance, more foundational work for Emscripten support in the Swift toolchain, a WASI fix for NSStrin… --- ## [\[Pitch\] Emscripten Target Support for Swift](https://forums.swift.org/t/pitch-emscripten-target-support-for-swift/85310)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 9\ **Last updated:** [May 30, 2026, 9:25am UTC](https://forums.swift.org/t/pitch-emscripten-target-support-for-swift/85310 "2026-05-30T09:25:14Z")
Swift already runs in the browser today. Using the WASI target with JavaScriptKit and browser-side WASI polyfills, the community has built projects ranging from ElementaryUI (a SwiftUI-inspired web framework) to real-tim… --- ## [Swift for Wasm April 2026 Updates](https://forums.swift.org/t/swift-for-wasm-april-2026-updates/86371)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [April 30, 2026, 3:29pm UTC](https://forums.swift.org/t/swift-for-wasm-april-2026-updates/86371 "2026-04-30T15:29:14Z")
Notable changes this month: Wasm-compatible swift-tar library, JavaScriptKit 0.50.0–0.51 releases with continued BridgeJS work and a new opt-in pointer-identity mode for SwiftHeapObject wrappers, WasmKit updates unifying… --- ## [Swift for Wasm March 2026 Updates](https://forums.swift.org/t/swift-for-wasm-march-2026-updates/85725)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [March 31, 2026, 2:31pm UTC](https://forums.swift.org/t/swift-for-wasm-march-2026-updates/85725 "2026-03-31T14:31:25Z")
Notable changes this month: JavaScriptKit release 0.49.0 with BridgeJS improvements, WasmKit continued Component Model work coupled with a few bug fixes, and ElementaryUI migrated its DOM interop to BridgeJS. Many thanks… --- ## [Embedded WASM undefined symbol: \_\_multi3](https://forums.swift.org/t/embedded-wasm-undefined-symbol-multi3/85673)
**Author:** [@purpln](https://forums.swift.org/u/purpln)\ **Replies:** 3\ **Last updated:** [March 30, 2026, 8:33am UTC](https://forums.swift.org/t/embedded-wasm-undefined-symbol-multi3/85673 "2026-03-30T08:33:28Z")
Before Swift 6.3, I had a custom function converting Float/Double to StaticString that was implemented on the JS side. I removed it because I saw that this conversion was made inside the Swift standard library. So I trie… --- ## [How to build Wasm SDK from source?](https://forums.swift.org/t/how-to-build-wasm-sdk-from-source/85678)
**Author:** [@taylorswift](https://forums.swift.org/u/taylorswift)\ **Replies:** 0\ **Last updated:** [March 29, 2026, 11:07pm UTC](https://forums.swift.org/t/how-to-build-wasm-sdk-from-source/85678 "2026-03-29T23:07:41Z")
i am desperately trying to obtain a wasm32-unknown-wasip1-threads SDK bundle that is compatible with the latest swift-6.3-RELEASE toolchain. i couldn’t figure out where to obtain such a bundle from official or unofficial… --- ## [WebAssembly with Embedded feature multithreading](https://forums.swift.org/t/webassembly-with-embedded-feature-multithreading/85574)
**Author:** [@purpln](https://forums.swift.org/u/purpln)\ **Replies:** 7\ **Last updated:** [March 27, 2026, 4:22pm UTC](https://forums.swift.org/t/webassembly-with-embedded-feature-multithreading/85574 "2026-03-27T16:22:09Z")
Currently I run Swift compiled for wasm32-unknown-none-wasm triple inside multiple web workers with SharedArrayBuffer memory between them. So my setup is multithreaded. I wanted to use conditional compilation to separat… --- ## [WebAssembly, some symbols are available with @\_extern(c) others not](https://forums.swift.org/t/webassembly-some-symbols-are-available-with-extern-c-others-not/85573)
**Author:** [@purpln](https://forums.swift.org/u/purpln)\ **Replies:** 2\ **Last updated:** [March 25, 2026, 12:32pm UTC](https://forums.swift.org/t/webassembly-some-symbols-are-available-with-extern-c-others-not/85573 "2026-03-25T12:32:31Z")
Got undefined symbol: \_\_builtin\_wasm\_tls\_size error on linking stage trying to compile: @\_extern(c, "\_\_builtin\_wasm\_tls\_size") private func \_\_builtin\_wasm\_tls\_size() -\> Int If I create C wrapper and call it from Swift… --- ## [Possible double-destruction bug for ~Copyable type when targeting WASM](https://forums.swift.org/t/possible-double-destruction-bug-for-copyable-type-when-targeting-wasm/85078)
**Author:** [@joehink](https://forums.swift.org/u/joehink)\ **Replies:** 6\ **Last updated:** [March 8, 2026, 11:25am UTC](https://forums.swift.org/t/possible-double-destruction-bug-for-copyable-type-when-targeting-wasm/85078 "2026-03-08T11:25:32Z")
I’m seeing different destruction behavior for a move-only type (~Copyable) when compiling for native vs WebAssembly. Native behavior matches expectations, but the WASM build appears to destroy the value twice. struct S… --- ## [Swift for Wasm February 2026 Updates](https://forums.swift.org/t/swift-for-wasm-february-2026-updates/85046)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [February 27, 2026, 12:50pm UTC](https://forums.swift.org/t/swift-for-wasm-february-2026-updates/85046 "2026-02-27T12:50:45Z")
Hello Swift community! Here's a summary of notable changes and improvements to Swift for WebAssembly projects during February 2026. This includes, but is not limited to BridgeJS reaching MVP in JavaScriptKit, preliminary… --- ## [Swift for Wasm January 2026 Updates](https://forums.swift.org/t/swift-for-wasm-january-2026-updates/84458)
**Author:** [@scottm](https://forums.swift.org/u/scottm)\ **Replies:** 0\ **Last updated:** [January 29, 2026, 6:39pm UTC](https://forums.swift.org/t/swift-for-wasm-january-2026-updates/84458 "2026-01-29T18:39:17Z")
Swift for Wasm January 2026 Updates I'm excited to share our recent progress by the Swift for WebAssembly community. Our number of active contributors is growing, and we're happy to see Simon Leeb announcing the launch … --- ## [Agent Skills: Expert recipes for Swift on WebAssembly](https://forums.swift.org/t/agent-skills-expert-recipes-for-swift-on-webassembly/84075)
**Author:** [@kateinoigakukun](https://forums.swift.org/u/kateinoigakukun)\ **Replies:** 1\ **Last updated:** [January 12, 2026, 9:58pm UTC](https://forums.swift.org/t/agent-skills-expert-recipes-for-swift-on-webassembly/84075 "2026-01-12T21:58:49Z")
Hi everyone, Many of us are now using AI coding agents like Cursor, Claude Code, and so on. While they are great for general Swift tasks, they often struggle with the specifics of Swift on WebAssembly. They might sugges… --- ## [Totally lost on how to call a member of a JavaScriptKit object](https://forums.swift.org/t/totally-lost-on-how-to-call-a-member-of-a-javascriptkit-object/83982)
**Author:** [@taylorswift](https://forums.swift.org/u/taylorswift)\ **Replies:** 1\ **Last updated:** [January 6, 2026, 6:05am UTC](https://forums.swift.org/t/totally-lost-on-how-to-call-a-member-of-a-javascriptkit-object/83982 "2026-01-06T06:05:49Z")
i have an instance of URLSearchParams that i am trying to pass to Swift code as a JSObject. to call the get(\_:) method of the JavaScript object, one must do something like this: let value: JSValue? = self.object.get?(k… --- ## [Swift for Wasm December 2025 Updates](https://forums.swift.org/t/swift-for-wasm-december-2025-updates/83778)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [December 19, 2025, 12:58pm UTC](https://forums.swift.org/t/swift-for-wasm-december-2025-updates/83778 "2025-12-19T12:58:59Z")
In the last month of the year things are quieter, but we still have a few updates for you! The general theme is continued: toolchain bug fixes, steady stream of improvements to JavaScript and Swift interop, polishing Was… --- ## [How to test Swift WebAssembly applications?](https://forums.swift.org/t/how-to-test-swift-webassembly-applications/83073)
**Author:** [@taylorswift](https://forums.swift.org/u/taylorswift)\ **Replies:** 14\ **Last updated:** [December 7, 2025, 2:17am UTC](https://forums.swift.org/t/how-to-test-swift-webassembly-applications/83073 "2025-12-07T02:17:56Z")
the official Swift WebAssembly book points us to carton for testing WebAssembly applications. but of course, that is severely out of date, as carton is now deprecated. i don’t need to run a full in-browser integration t… --- ## [Deprecating \`swiftwasm/carton\` in favor of JavaScriptKit's SwiftPM Plugin](https://forums.swift.org/t/deprecating-swiftwasm-carton-in-favor-of-javascriptkits-swiftpm-plugin/83460)
**Author:** [@kateinoigakukun](https://forums.swift.org/u/kateinoigakukun)\ **Replies:** 0\ **Last updated:** [November 29, 2025, 11:52am UTC](https://forums.swift.org/t/deprecating-swiftwasm-carton-in-favor-of-javascriptkits-swiftpm-plugin/83460 "2025-11-29T11:52:46Z")
Hi everyone, With the recent improvements in the SwiftPM Plugin for JavaScriptKit, I think it's time to formally deprecate swiftwasm/carton. What carton has historically provided When we first introduced carton, it cov… --- ## [Swift for Wasm November 2025 Updates](https://forums.swift.org/t/swift-for-wasm-november-2025-updates/83450)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [November 28, 2025, 3:35pm UTC](https://forums.swift.org/t/swift-for-wasm-november-2025-updates/83450 "2025-11-28T15:35:58Z")
I'm excited to provide an update on our latest progress in the Swift for Wasm ecosystem! This month the community focused on improvements to Swift and JavaScript interop, debugger support in WasmKit, and Wasm compatibili… --- ## [Installing Swift Wasm SDK 6.2-RELEASE kinda doesn't work, missing: Swift SDK metadata file](https://forums.swift.org/t/installing-swift-wasm-sdk-6-2-release-kinda-doesnt-work-missing-swift-sdk-metadata-file/83359)
**Author:** [@karloscarweber](https://forums.swift.org/u/karloscarweber)\ **Replies:** 1\ **Last updated:** [November 21, 2025, 11:02pm UTC](https://forums.swift.org/t/installing-swift-wasm-sdk-6-2-release-kinda-doesnt-work-missing-swift-sdk-metadata-file/83359 "2025-11-21T23:02:33Z")
Hi Friends! With the steady adoption of Swift 6.2 over here in the land of the mountain tops, I'm starting to see a new ominous error when installing the Swift SDK in our CI environment. One of the errors I get is: war… --- ## [Swift for Wasm Community Hour (3rd of December 2025)](https://forums.swift.org/t/swift-for-wasm-community-hour-3rd-of-december-2025/83347)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 0\ **Last updated:** [November 21, 2025, 11:51am UTC](https://forums.swift.org/t/swift-for-wasm-community-hour-3rd-of-december-2025/83347 "2025-11-21T11:51:36Z")
I'm excited to announce the inaugural Swift for Wasm Community Hour! We welcome everyone at this event, no matter your background or experience. This is an open space to ask questions and to learn from each other. We ki… --- ## [Swift for Wasm September-October 2025 Updates](https://forums.swift.org/t/swift-for-wasm-september-october-2025-updates/82966)
**Author:** [@Max\_Desiatov](https://forums.swift.org/u/Max_Desiatov)\ **Replies:** 9\ **Last updated:** [November 6, 2025, 2:31am UTC](https://forums.swift.org/t/swift-for-wasm-september-october-2025-updates/82966 "2025-11-06T02:31:35Z")
I'm excited to share an update on the latest progress in the Swift for WebAssembly ecosystem! Last two months of community's work were mainly focused on polishing the Swift toolchain, developing new features in our prima… [Next page](https://forums.swift.org/c/platform/swift-for-webassembly/71.md?page=1)