Thomas Preston-Werner (born October 28, 1979) is an American billionaire software developer and entrepreneur.
He is an active contributor within the open-source development community, most prominently in the San Francisco Bay Area, where he lives.
He is best known as the founder and former CEO of GitHub, a Git repository web-based hosting service, which he co-founded in 2008 with Chris Wanstrath and PJ Hyett.
He resigned from GitHub in 2014 when an internal investigation concluded that he and his wife harassed an employee.
Preston-Werner is also the creator of the avatar service Gravatar, the TOML configuration file format and the Semantic Versioning Specification (SemVer) Preston-Werner lives in San Francisco with his wife Theresa and their sons.His wife is a former graduate student in cultural anthropology known for her involvement in historical research and social subjects.