This is the source code for the Python Install Manager app.

For information about how to use the Python install manager, including troubleshooting steps, please refer to the documentation at docs.python.org/using/windows.

The original PEP leading to this tool was PEP 773.

To build and run locally requires pymsbuild and a Visual Studio installation that includes the C/C++ compilers.

> python -m pip install pymsbuild
> python -m pymsbuild
> python-manager\py.exe ...

Any modification to a source file requires rebuilding. The .py files are packaged into an extension module. However, see the following section on tests, as test runs do not require a full build.

For additional output, set %PYMANAGER_DEBUG% to force debug-level output. This is the equivalent of passing -vv, though it also works for contexts that do not accept options (such as launching a runtime).

To run the test suite locally:

> python -m pip install pymsbuild pytest
> python -m pymsbuild -c _msbuild_test.py
> python -m pytest

This builds the native components separately so that you can quickly iterate on the Python code. Any updates to the C++ files will require running the pymsbuild step again.

To produce an (almost) installer app package:

> python -m pip install pymsbuild
> python make-all.py

This will rebuild the project and produce MSIX, APPXSYM and MSI packages.

You will need to sign the MSIX package before you can install it. This can be a self-signed certificate, but it must be added to your Trusted Publishers. Alternatively, rename the file to .zip and extract it to a directory, and run Add-AppxPackage -Register <path to dir>\appxmanifest.xml to do a development install. This should add the global aliases and allow you to test as if it was properly installed.

Contributions are welcome under all the same conditions as for CPython, see the Python Developer's Guide for more information.

The release manager for the Python Install Manager on Windows is whoever is the build manager for Windows for CPython. Currently, this is @zooba.

Releases are made as needed, with prereleases made at the release manager's judgement. Due to the broad user base of PyManager, we have to avoid significant changes to its interface, which means feature development is heavily restricted.

PyManager uses the two digit year as the first part of the version, with the second part incrementing for each release. This is to avoid any sense of features being tied to the version number, and to avoid any direct association with Python releases.

The two digit year is used because MSI does not support major version fields over 256. If/when we completely drop the MSI, we could switch to four digit years, but as long as it exists we have to handle its compatibility constraints.

Copyright © 2025 Python Software Foundation. All rights reserved.

See the LICENSE for information on the terms & conditions for usage, and a DISCLAIMER OF ALL WARRANTIES.

All trademarks referenced herein are property of their respective holders.