A combination photo shows CEO of OpenAI Sam Altman (L)
A combination photo shows CEO of OpenAI Sam Altman (R) on May 26, 2023. and Elon Musk on May 21, 2025 in Washington, DC. JOEL SAGET /Chip Somodevilla/Getty Images

OpenAI said Friday it will stop supplying AI models directly to Cursor, the coding tool Elon Musk's SpaceX bought for $60 billion earlier this month, with access ending November 12.

The company gave its reasoning in a statement: it "cannot be confident that SpaceX will use our technology within our terms of service," pointing to what it called a pattern of Musk's companies violating contracts. It cited Musk's own admission under cross-examination this year that xAI had trained on OpenAI's outputs through distillation. OpenAI said it would also withhold future models, including its upcoming Astra release, from Cursor before the cutoff date.

SpaceX closed its all-stock purchase of Cursor's parent company, Anysphere, on August 14, folding the coding tool into a new SpaceXAI division. The deal, first agreed in April and finalized after SpaceX's IPO, is the largest acquisition of a venture-backed startup on record.

Cursor co-founder and CEO Michael Truell responded on X the same night, saying OpenAI models account for roughly 5% of Cursor's user traffic and that the two companies were in talks to resolve the dispute. He called OpenAI's platform "neutral infrastructure" the company had trusted for years.

Musk was less measured. In a weekend post on X, he dismissed the decision and accused OpenAI chief executive Sam Altman and president Greg Brockman, in vulgar terms, of having "stolen" a nonprofit — repeating a claim he has pressed since suing the pair in 2024. Musk lost that suit earlier this year and has said he will appeal.

The rupture is the latest in a string of AI labs cutting rivals' tools off from their models. Anthropic blocked the coding assistant Windsurf from its Claude models last year amid a planned OpenAI acquisition of that company. This time, Anthropic co-founder Tom Brown said on X that Anthropic would keep expanding compute for Claude inside Cursor, calling it "a trusted partner."

For now, Cursor users who rely on OpenAI's models can keep working through their own API keys after November 12, according to OpenAI, and the company said it plans additional support for developers during the transition.