You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.

py3toolset
1.2.19a0

This version was deleted from PyPI around 2025-09-12. Installing fails with:
$ pip3 install py3toolset==1.2.19a0 ERROR: Could not find a version that satisfies the requirement py3toolset==1.2.19a0
View other deleted versions of py3toolset

Install through StableBuild

You can install this package from StableBuild's PyPI snapshots from before the version was deleted:
pip3 install \ -i https://YOUR_API_KEY.pypimirror.stablebuild.com/2025-09-11/ \ py3toolset==1.2.19a0
Sign up for StableBuild to get an API key (it's free and takes <60 seconds!)

Or, download files manually

And install manually via pip:
py3toolset-1.2.19a0-py3-none-any.whl (20.3KB)