The best replacement for github for windows is git.

The best alternatives to github for windows are rated as following:
★★★★★  git
★★★★  sourcetree
★★★  tortoisegit
★  smartgit

Your alternative for github for windows is not listed? Suggest!
Speaking about github for windows, one probably shouldn't forget about bitbucket.

Other search terms related to github for windows and their ratings are:
★★★★★ bitbucket
You have in mind a companion for github for windows and it is not yet here? Propose!



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github for windows
git
sourcetree