Anthropic Built Its Own Version Control System After Code Merges Exploded to 30,000 a Day

Redesigning Source Control at Anthropic

Anthropic replaced Git with a custom centralized system called Scion after daily code merges surged from 2,500 in May 2026 to over 30,000 by September. The main branch history alone is nearly 100 GB, and the company performs 25 million checkouts per day, which would generate over 600 PB of Git traffic. A seven-person team completed the migration in five months, drawing on prior art from Google's Piper and Meta's Sapling.