GitHub is a vast code repository that has become popular with developers and companies hosting their projects, documentation, and code. Apple, Amazon, Google, and many other big tech companies use GitHub. Microsoft is the top contributor to the site, and has more than 1,000 employees actively pushing code to repositories on GitHub. Microsoft even hosts its own original Windows File Manager source code on GitHub. The service was last valued at $2 billion back in 2015, but it’s not clear exactly how much Microsoft has paid to acquire GitHub.