Tom Preston-Werner

Following his resignation from GitHub, Preston-Werner sold his shares in the company to Microsoft. Along with a team of former GitHub co-founders and executives, Preston-Werner then cofounded Chatterbug, a software for language-learning . In 2018, Chatterbug cofounder Scott Chacon announced an 8 million series A funding round for the company, financed by himself and Preston-Werner.

Julie Ann Horvath, a GitHub programmer, alleged in March 2014 that Tom Preston-Werner and his wife Theresa engaged in a pattern of harassment against her that led her to leave the company. GitHub initially denied Horvath's allegations, then following an internal investigation, confirmed some of the claims. Preston-Werner resigned. GitHub's new CEO Chris Wanstrath said the "investigation found Tom Preston-Werner in his capacity as GitHub’s CEO acted inappropriately, including confrontational conduct, disregard of workplace complaints, insensitivity to the impact of his spouse's presence in the workplace, and failure to enforce an agreement that his spouse should not work in the office."

Preston was one of the initial members of the San Francisco group IcanhazRuby or ICHR, after he became a regular member of the San Francisco Ruby Meetups. He continued until the meetings became overwhelmed by venture capital investors searching for talent; this prompted him to seek more private gatherings. On April 8, 2011 he also started a conference called CodeConf, by means of GitHub's influence in the coding community.

In an article published by Hacker Monthly in 2010, Preston wrote about his passion for ensuring that developers document the code they write so others can easily understand how it works.

In 2010 Preston-Werner read a comment on Twitter insulting the quality of GitHub's search function. This prompted him to overhaul the service's search, drawing on his experience having worked at Powerset.

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, the static site generator software Jekyll, and the Semantic Versioning Specification (SemVer)

In 2008 Tom Preston-Werner spoke about the application of conceptual algorithms to higher-level thinking patterns, rather than solely to coding patterns.

Preston-Werner co-founded GitHub in 2008 with Chris Wanstrath, PJ Hyett and Scott Chacon, as a place to share and collaborate on code.

In 2004, Preston-Werner founded Gravatar, a service for providing globally unique avatars that follow users from site to site. The company grew to about 32,000 users in 2007, when Preston-Werner sold the company to Automattic. In 2005 he moved to San Francisco to work at Powerset, a natural language search engine. Powerset was acquired by Microsoft. Preston-Werner declined a $300,000 bonus and stock options from Microsoft so that he could focus on GitHub.

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.