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

fastjet
3.3.4.0rc6

This version was deleted from PyPI around 2024-05-15. Installing fails with:
$ pip3 install fastjet==3.3.4.0rc6 ERROR: Could not find a version that satisfies the requirement fastjet==3.3.4.0rc6
View other deleted versions of fastjet

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/2024-05-14/ \ fastjet==3.3.4.0rc6
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:
fastjet-3.3.4.0rc6.tar.gz (3.0MB)