No sensitive customer data or credentials were involved or exposed. This was a release packaging issue caused by human error, not a security breach. This statement from an Anthropic spokesperson highlights the nature of the recent leak involving the Claude Code, which has sent ripples through the tech community.
On March 31, 2026, Anthropic accidentally leaked the source code for Claude Code, exposing around 500,000 lines of code across roughly 1,900 files. The leak occurred when the company mistakenly uploaded all of Claude Code’s original code to NPM instead of only the finished version.
The leaked code includes features such as a multi-agent coordinator and a virtual pet system, as well as a mode codenamed ‘Kairos’ that allows for background sessions. Notably, the leak also revealed the existence of a new model internally named ‘Capybara’.
Roy Paz, a technology expert, commented, “Usually, large companies have strict processes and multiple checks before code reaches production, like a vault requiring several keys to open.” This incident raises questions about the internal protocols at Anthropic.
The leak has been described as a ‘human error’ due to a misconfiguration, and it is considered potentially more damaging than a previous leak of a draft blog post. The developer community has reacted with significant excitement and activity, likening the incident to an accidental open-source event.
“The leak of the Claude Code source code has made the whole network restless,” remarked an anonymous source within the industry. This sentiment reflects the broader implications of the leak, as it potentially allows competitors to reverse-engineer Claude Code’s agentic harness.
This isn’t the first time Anthropic has inadvertently leaked details about Claude Code; a similar breach occurred in February 2025. The cumulative effect of these leaks raises concerns about the company’s handling of sensitive information.
As the situation develops, the tech community will be closely monitoring any further statements from Anthropic regarding the leak and its implications for the future of Claude Code and its associated models.
