Self-hosted Pyodide

Build a self-hosted Pyodide distribution with additional PyPI packages, ready to upload to S3 (or any static file host).

What this does

1. Downloads the Pyodide release tarball for each version found in requirements/
2. Downloads extra PyPI packages (pure-Python wheels) from requirements/{version}.txt
3. Registers the extra wheels in pyodide-lock.json so Pyodide can find them
4. Outputs everything to dist/v{version}/full/ — ready to sync to S3

The resulting S3 structure supports URLs like:

https://pyodide.company.com/v0.27.5/full/pyodide.js

Usage

1. Add PyPI packages

Create requirements/{version}.txt (e.g. requirements/0.27.5.txt) for each Pyodide version you want to build, and list the packages you want:

xlwings  # required
python-dotenv  # required
black  # required

Unless you need a specific version of the package, adding packages without pinning the version is ok as they will be pinned in pyodide-lock.json. Only pure-Python wheels py3-none-any) are supported. Platform-specific or C-extension packages must be built for Emscripten/WASM separately.

2. Run the build

Install uv if you haven't yet:

• Windows: powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
• macOS / Linux: curl -LsSf https://astral.sh/uv/install.sh | sh

Then run the build script:

uv run build.py

The Pyodide tarball is cached in the current directory to avoid re-downloading on subsequent runs.

3. Upload to S3

Install the aws CLI.

aws s3 sync ./dist/ s3://my-pyodide-bucket/

Pair with a CloudFront distribution pointing at the bucket.

• Set CORS headers: Bucket → Permissions → CORS configuration, e.g.,:

  [
    {
      "AllowedOrigins": ["*"],
      "AllowedMethods": ["GET", "HEAD"],
      "AllowedHeaders": ["*"]
    }
  ]

• Set Cache-Control: immutable headers on the objects for optimal performance.

• For regulated use cases where the Python environment must be frozen at a point in time consider enabling S3 Object Lock (WORM mode) on the bucket for write-once guarantees.