I have not found any repositories to match the wonderful visuals that GitHub provides when viewing the comparison between files over a commit/pull request. If there was an offline option of using this same feature/API, integrated (in)dependently, I believe it would help in software production.
Although this is very similar to what
git provides through the
git diff command, there are not many who this tool, and it does not contain the same level of quality and ease of usage, especially in the debugging process.
If this subject leads to some release or solution, it should be made more discoverable. If it is not something meant to be exposed, then this is totally understandable. Lastly, if you happen to know where this resource (or any related project) resides, please leave a response!