Intent to prototype: WebAssembly Component Model

[Ryan Hunt]

Summary:

The WebAssembly Component Model is a proposal at the W3C WebAssembly CG/WG.

Wasm components have high level types that enable them to import web APIs and export an API useable by JS (and other languages). Wasm components are internally implemented using wasm modules along with an ABI for passing/receiving values.

We want to experiment with this as a way to improve web page performance for users and simplify the experience for developers when using wasm. See this blog post for more details [1].

[1] https://hacks.mozilla.org/2026/02/making-webassembly-a-first-class-language-on-the-web/

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=wasm-components

Specification: https://github.com/WebAssembly/component-model

Standards Body: W3C WebAssembly CG+WG

Platform Coverage: All platforms

Preference: javascript.options.wasm_components

DevTools Bug: N/A

Extensions Bug: N/A

Use Counter: N/A

Standards-Positions Discussion: https://github.com/mozilla/standards-positions/issues/1454

Other Browsers:
- Blink: Evaluating (https://issues.chromium.org/issues/474661098)
- WebKit: No position

web-platform-tests:
- No WPTs yet, I hope to start writing some as part of prototyping.
- There is an extensive wast testsuite (WebAssembly's reference test format): https://github.com/WebAssembly/component-model/tree/main/test