Software archives

Software Heritage is an ambitious project archiving all of the source code of humanity. Has a browsable interface of the total archive.
roam:archive.org has a dedicated section for software. They are especially nice for scouring historical versions of software.
Arch Linux has an archive that keeps the snapshots, packages, and repos for a few years before uploading it to their historical archive.
Nix package manager has a binary cache. According to one of the contributors, it makes up 120TB as of 2021-07-25.
Guix package manager has a binary cache primarily maintained with its homegrown continuous integration software.
roam:F-Droid has an archive for its compiled apps. From one of their comments, it is sitting at ~390GB as of 2021-07-25.
FOSS Torrents is a torrent repository of precompiled software projects.