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

neqsim
2.2.31

This version was deleted from PyPI around 2025-08-20. Installing fails with:
$ pip3 install neqsim==2.2.31 ERROR: Could not find a version that satisfies the requirement neqsim==2.2.31
View other deleted versions of neqsim

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/2025-08-19/ \ neqsim==2.2.31
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Or, download files manually

And install manually via pip:
neqsim-2.2.31-py3-none-any.whl (62.3MB)
neqsim-2.2.31.tar.gz (11.5KB)