Basic Usage#

Installing packages with micropip#

micropip can install following types of packages:

  1. Pure Python packages

Pure Python packages are packages that do not have any compiled code. Most pure Python packages can be installed directly from PyPI with micropip.install if they have a pure Python wheel. Check if this is the case by trying micropip.install("package-name").

  1. Python packages that contain C-extensions

If a package has C-extensions (or any other compiled codes like Rust), it will not have a pure Python wheel on PyPI.

Trying to install such a package with micropip.install will result in an error like:

ValueError: Can't find a pure Python 3 wheel for 'tensorflow'.
You can use `micropip.install(..., keep_going=True)`to get a list of all packages with missing wheels.

To install such a package, you need to first build a Python wheels for WASM/Emscripten for it.

Note that pyodide provides several commonly used packages with pre-built wheels. Those packages can be installed with micropip.install("package-name").


You can find a list of packages with pre-built wheels in the Pyodide documentation. If your package is not in the list, you can build a wheel for it yourself. See the Building packages section of the Pyodide documentation for more information.


import micropip

# snoballstemmer is a pure Python package
# and has a pure Python wheel on PyPI
# so it can be installed directly
await micropip.install("snowballstemmer")

# numpy is a package that has C-extensions
# and does not have a pure Python wheel on PyPI
# but it is provided by Pyodide
await micropip.install("numpy")

# It is also possible to install from
# - arbitrary URLs
await micropip.install("https://.../package.whl")
# - local files inside the Pyodide virtual file system
await micropip.install("emfs://.../package.whl")

Advanced usage#

You can pass multiple packages to micropip.install:

await micropip.install(["pkg1", "pkg2"])

You can specify additional constraints:

await micropip.install("snowballstemmer==2.2.0")
await micropip.install("snowballstemmer>=2.2.0")
await micropip.install("snowballstemmer[all]")

micropip does dependency resolution by default, but you can disable it, this is useful if you want to install a package that has a dependency which is not a pure Python package, but it is not mandatory for your use case:

await micropip.install("pkg", deps=False)