You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.
mrmustard was reported malicious
OSV:MAL-2026-11049 - Malicious code in mrmustard (PyPI)

mrmustard
1.0.0a1

This version was deleted from PyPI around 2026-07-24. Installing fails with:
$ pip3 install mrmustard==1.0.0a1 ERROR: Could not find a version that satisfies the requirement mrmustard==1.0.0a1
View other deleted versions of mrmustard

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/2026-07-23/ \ mrmustard==1.0.0a1
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:
mrmustard-1.0.0a1-py3-none-any.whl (415.0KB)
mrmustard-1.0.0a1.tar.gz (267.3KB)