Anthropic replaces Git with in-house source control for its monorepo

Anthropic says it fully migrated its monorepo from Git to an in-house version control system called Scion in five months. The company reports merging over 30,000 code changes per day as of September, compared with around 2,500 per day in May 2026. Scion moves commits, merges and history queries to servers, while clients fetch files as needed and retain a bounded local cache. Internal jobs can query source control through APIs without maintaining local repositories. The design assumes clients remain online; Anthropic says its unusually heavy use of Claude to write software makes its workload different from that of most organizations.