Redesigning source control at Anthropic

Anthropic has redesigned its source control system, moving away from Git to a custom alternative due to a dramatic increase in code changes. The company observed a surge from approximately 2,500 code changes merged per day in May 2026 to over 30,000 per day by September. This shift was also influenced by Anthropic's extensive use of adversarial review, which, despite its effectiveness, sometimes required engineers to guide Claude away from over-engineering.

Anthropic's custom source control system is a direct response to a tenfold increase in daily code changes, unlike other companies that adapt existing Git solutions.