Stash that
Bitbucket
It's purely coincidental that GitHub is now offering a 99.95 per cent uptime guarantee after the downtime experienced by Amazon Web Services customers on Tuesday. GitHub's stability commitment applies to its new Business tier, priced at $21 per user per month, which includes SAML single sign-on, automated provisioning and …
Yes you can, but you don't get a management interface, or any of the additional functionality outside of the git CLI like issue tracking, wikis, pull requests, web viewer/editor etc.
Having said that, GitHub Enterprise is ridonculously expensive. Other alternatives such as Gitlab or Gogs are much more affordable (Gogs is very close to being a GitHub clone and is open source.)