Anthropic has replaced Git with its proprietary version control system, Scion, completing a full migration of its monorepo in five months. The shift was driven by development infrastructure bottlenecks as daily code merges surged from approximately 2,500 in May to over 30,000 by September, exceeding the scale for which Git was originally designed. Built by a seven-person team, Scion reduces CPU and memory usage by roughly 200x compared to previous Git mirror solutions and cuts code pull times for CI and research tasks from minutes to seconds. Anthropic stated that Scion is not intended as a general-purpose Git replacement and is currently sharing only the design approach.