GitLab and Bitbucket are more about private companies and their private hosting for doing their actual private work. GitHub does that too, of course. But they

GitLab and Bitbucket are more about private companies and their private hosting for doing their actual private work. GitHub does that too, of course. But they are also basically a social networking website for individuals and organizations in the software industry. Prominent companies put code on GitHub because that's how you maintain a public presence in the developer community today. Even though the GitHub repos are more often than not mirrors, with the code actually being developed with internally-hosted repos and tooling. So as far public destinations for open source code, GitHub has that market pretty sewn up for now. However, there's lots of competition in the "charging money for private services" market. Atlassian is a giant in the enterprise world, and I'm sure GitLab is doing well too. GitHub sells private services too, of course. Lots of people argue that Bitbucket's tooling is better, and even the paid version of GitLab is insanely cheaper... but GitHub does have an advantage in being able to leverage everyone's familiarity with it.