Anthropic Built Its Own Source Control System to Replace Git After Coding Velocity Surge

It is an in-house source control system built as an alternative to Git, designed to absorb very large volumes of code changes and daily checkouts. It resembles a reinvention of centralized source control along the lines of Subversion.

Because merged changes grew from about 2,500 per day in May 2026 to over 30,000 in September, with a main branch history near 100 GB and 25 million daily checkouts, workloads Git was not designed to handle efficiently.

Not necessarily. Anthropic reached these volumes through heavy agentic coding, and the migration took five months with a seven-person team. Smaller regional teams may benefit more from optimizing CI/CD pipelines and governing agent usage before building custom source control.

The source suggests the introduction of Fable/Mythos class models is likely a key factor in the increased coding velocity, while noting the chart shows public release dates, not when models became available internally.