As of May 2026, more than 80% of the code we merge into Anthropic’s codebase was authored by Claude.
AnthropicPublished by the organization itself (post), no named author
Post: When AI builds itself, Anthropic (the Anthropic Institute, on anthropic.com), June 4, 2026.
Anthropic sells AI or agent tooling, so it has a reason to publish flattering numbers about AI. The passage stays in the archive; read it with that in mind.
Checked against the source by a first reader, then confirmed independently by a second reader who fetched the source without seeing the first reader's notes (Independent review agent (Claude Sonnet), blind second pass from passage text and citation only, no repository access, 2026-10-31).
The sentence is in the body text: 'Claude writes a significant proportion of Anthropic's code. As of May 2026, more than 80% of the code we merge into Anthropic's codebase was authored by Claude.' It matches after curly apostrophes were normalized to straight ones. The page is Anthropic's own publication.
Anthropic, “When AI builds itself”, Anthropic (the Anthropic Institute, on anthropic.com), 2026-06-04. https://www.anthropic.com/institute/recursive-self-improvement Archived at https://the-ai-record.com/passages/anthropic-may-2026-more-than-80-code-merge-2026
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