Anthropic reportedly leaked 512,000 lines of Claude Code source code yesterday, and what followed over the next 12 hours was wild.
At 4 AM, Anthropic pushed an update to npm that accidentally included a 60 MB debugging file containing their entire codebase. Just 23 minutes later, researcher Chaofan Shou spotted it, downloaded the zip, and posted about it on X. Within 6 hours, the post had reached 3 million views. By the time Anthropic’s team woke up, the code had already been forked more than 41,000 times across GitHub. Anthropic began issuing DMCA takedowns, but by then it was too late.
One of the people who jumped on it was Korean developer Sigrid Jin, Claude Code’s biggest power user. According to The Wall Street Journal, he burned through 25 billion tokens last year. After reading the leaked code, he rewrote the entire thing in Python in just 8 hours. That repo reached 30,000 stars faster than any GitHub project in history. Then he rewrote it again in Rust, and that version now has 49,000 stars.
Meanwhile, someone mirrored the code to a decentralized platform with a single message: “will never be taken down.” In other words, the code is permanent, and Anthropic cannot get it back.
The part I cannot stop thinking about is this: Anthropic had built something called “Undercover Mode,” a feature designed specifically to stop Claude from accidentally leaking internal secrets. They shipped an anti-leak system inside their own product, then leaked their own source code in a .map file. The irony is brutal.