He is best known for being the co-founder and former CEO of the company GitHub. He founded the company in 2007 with Chris Wanstrath when they were both working at the Web development framework company Ruby on Rails. Preston-Werner resigned from the company in 2014 after harassment accusations from one of the company's programmers. GitHub allows multiple coders to work on the same piece of code and not lose track of their changes and has been valued at $2 billion. They have had more than 11 million users work on more than 29 million projects. GitHub's clients include Microsoft, NASA, Walmart, and the governments of the United States and the United Kingdom.
In 2012 GitHub raised the largest first round of venture capital funding at $100 million. Preston-Werner also created the avatar service Gravatar which he sold to Matt Mullengweg, the founder of WordPress. He went on to co-found the non-profit organization Codestarter which donates computers to child programmers. On June 4, 2018, Microsoft agreed to acquire GitHub for $7.5 billion. As a result of the acquisition, Tom Preston-Werner was given $1.25 billion worth of Microsoft stock. Two of his co-founders also received more than $1 billion in Microsoft from the sale. The largest shareholder, Chris Wanstrath, received $1.5 billion.
