OpenAI models turn out to be about 5 percent of Cursor's traffic

The loudest AI breakup of the week came with a deflating footnote. OpenAI is cutting off Cursor, and Cursor’s CEO answered with a number: OpenAI models carry about 5 percent of the editor’s AI traffic.

The breakup, quantified

OpenAI announced it is ending Cursor’s model access after the coding tool’s acquisition by SpaceX, with a proposed cutoff of November 12. The company’s stated reasons center on Elon Musk’s history with contracts, from ending Twitter’s data-sharing agreement with OpenAI to allegedly training Grok on other labs’ model outputs. The announcement drew 13.7 million views on X. Musk’s response, in his own words: “I couldn’t care less. Scam Altman and Greg Stockman are utterly untrustworthy.”

Cursor CEO Michael Truell’s 5 percent figure reframes the stakes. A day earlier this read as a serious blow to a tool millions of developers use. In traffic terms, it is a minority provider leaving.

Anthropic moves in

Before the door closed, Anthropic publicly stepped through it. Co-founder Tom Brown called Cursor a trusted partner since Sonnet 3.5 and pledged to keep expanding Claude compute for Cursor. The practical outcome of the feud: the editor loses a 5 percent provider, and that provider’s biggest rival commits to filling any gap.

The number is also a data point about the coding-tools market that goes beyond this dispute. Model providers have been treated as interchangeable infrastructure by the tools built on top of them, and the 5 percent share suggests developers inside Cursor had already voted with their usage. For OpenAI, the cutoff costs little revenue; the question is whether making model access contingent on corporate relationships pushes more tools to diversify away from every single provider.