WebAssembly

    Use WebAssembly in your extension without custom bundler setup.

    Extension.js ships with built-in WebAssembly defaults in its Rspack pipeline, so common wasm workflows work out of the box.

    When WebAssembly is a good fit

    • Your extension runs compute-heavy tasks (parsing, media, OCR, transforms).
    • You need near-native performance for hot code paths.
    • You are reusing existing wasm modules from web projects.

    WebAssembly capabilities

    CapabilityWhat it gives you
    Built-in wasm pipeline defaultsRun common wasm flows without manual bundler wiring
    Async wasm supportLoad .wasm modules in extension contexts
    Runtime compatibility helpersHandle common wasm ecosystem asset patterns
    Regular command workflowUse wasm with the same dev and build commands

    What Extension.js enables

    The wasm plugin configures:

    • experiments.asyncWebAssembly = true
    • .wasm in module resolution extensions
    • runtime asset aliases for common wasm ecosystems (for example ffmpeg, imagemagick wasm, tesseract wasm)

    This reduces boilerplate when importing wasm modules from extension scripts/pages.

    How to use

    Use wasm modules in your extension code as part of regular development/build flows:

    npm
    pnpm
    yarn
    npx extension dev ./my-extension

    You can also test against a known public sample:

    npm
    pnpm
    yarn
    npx extension@latest dev https://github.com/GoogleChrome/chrome-extensions-samples/tree/main/functional-samples/cookbook.wasm-helloworld-print

    Typical use cases

    • compute-heavy parsing/transforms
    • media processing pipelines
    • OCR / image processing workflows
    • performance-sensitive algorithms shared across web/runtime contexts

    Best practices

    • Keep wasm modules focused on hot paths; keep orchestration logic in JavaScript/TypeScript.
    • Validate output size and load timing for extension contexts (background, content scripts, pages).
    • Test wasm-heavy flows across browser targets you ship (chrome, edge, firefox).

    Next steps