Distribution:Git
From Game Making Tools Wiki
Forms
You can store and interact with git repositories wherever you wish, but there're some platforms availible that add handy features like issue reporting, wikis, easy code browsing, etc.
Gitea
Gitea (Git + tea, apparantly) is a self-host Git thing like Gitlab, but it is less demanding on server/host resources. Supposed to be able to run on a RaspberryPi, so within 1GB of RAM). Interface is verry Githubby.
Github
The most popular, but centralised.
Gitlab
Gitlab is somewhat like Github, but you can self-host it. They are working towards making these individual gitlab setups federate too, or at least be able to intermingle a bit, using Wikipedia:ActivityPub which is cool!