The core functionality behind git last-modified was written by GitHub over many years (originally called blame-tree in GitHub’s fork of Git), and is what has powered our tree-level blame since 2012. Earlier this year, we shared those patches with engineers at GitLab, who tidied up years of development into a reviewable series of patches which landed in this release.

The free software ethos at its finest, this is enough to make a grown man cry 🥹

PSA

git the FLOSS software is completely independent of github, the MS-owned web platform.
git was originally written by Linus Torvalds and can be selfhosted easily without additional software. Or be used locally.