Artificial intelligence firm Anthropic has accidentally revealed the source code for its popular coding tool Claude Code.

The leak occurred Tuesday morning when the company published version 2.1.88 of Claude Code to the public npm registry and inadvertently included a source map file, exposing more than 500,000 lines of code and nearly 2,000 files. A link to an archive containing the files was posted to X by security researcher Chaofan Shou, attracting more than 27 million views.

Claude AI is a versatile AI tool capable of answering questions, generating creative content like stories and poems, translating languages, transcribing and analyzing images, writing code, summarizing text and engaging people in natural, interactive conversations.  

(Disclosure: Ziff Davis, CNET's parent company, in 2025 filed a lawsuit against OpenAI, alleging it infringed Ziff Davis copyrights in training and operating its AI systems.)

An Anthropic spokesperson confirmed the leak, saying it was caused by human error and that the company is taking steps to prevent a recurrence.

"Earlier today, a Claude Code release included some internal source code," the spokesperson said. "No sensitive customer data or credentials were involved or exposed."

While Claude Code has reportedly been reverse-engineered, the leak provides developers with a rare look at the roadmap for perhaps Anthropics' most popular product, allowing competitors to gain insight into the coding tool's underpinnings.

The tool has seen a surge in popularity in recent months, with the Claude Code app experiencing a viral moment over the holidays as people discovered its vibe coding capabilities. Anthropic launched a Super Bowl ad campaign attacking rival OpenAI for its decision to put ads in its free and low-cost ChatGPT plans.