Every software system used at Gitlab
Gitlab has been pretty great so far, but the code review tooling is so poor I think I need to look elsewhere. The pull request pages take forever to load, they can't handle pull requests with over 800 lines well at all. It will collapse files with over 100-200 lines of changes for seemingly no reason (hiding the comments within them). You can't ignore whitespace in diffs, and the comments disappear from the diff if they push new commits, you need to look at them in the overview again.