GitLab is open core, GitHub is closed source
Disclosure: I'm the CEO of GitLab and we compete with GitHub.
We think of ourselves as an open source company but a commenter on Hacker News rightly remarked that calling it an open core company is more accurate https://news.ycombinator.com/item?id=12129626
We ship GitLab CE which is open source and GitLab EE that is closed source. By the way, the GitLab EE code and issue tracker are publicly viewable and the license allows modifications, but you do need a subscription from us.
Another point of confusion is that many people assume that GitHub is open source http://stackoverflow.com/questions/24254324/is-github-com-source-code-open-source But their only downloadable version called GitHub Enterprise Edition TODO LINK is closed source.
Their hosted service GitHub.com is free for open source projects and has fundamentally improved open source collaboration. I wanted to make sure people understood the difference between hosting open source and open source software.
At TODO in this VIDEO (LINK TODO) you see someone asking the same question. Interestingly they also encrypt their source code with https://www.rubyencoder.com/ and discouraged to hosting public repositories by other parties, like for example large open source projects hosting their own.
Of course GitHub has every right to close and encrypt their source code. Also note that GitHub is very actively contributing to open source themselves, including git, libgit2, Atom, Hubot, and many other projects. We use software they open sourced to make GitLab.