OpenAI is ending developer access to its AI models on Cursor, the coding assistant that Elon Musk’s SpaceX acquired earlier this month, escalating a decade-long rivalry between Musk and OpenAI CEO Sam Altman.
According to CNBC, OpenAI has set a proposed shutoff date in November and says it will not supply Cursor with any future models as the current arrangement winds down. Financial filings show SpaceX completed its $60 billion acquisition of Cursor on August 14.
OpenAI models account for roughly 5 percent of Cursor’s user traffic, Cursor CEO Michael Truell said in a post on X Friday night.
“OpenAI models serve about 5% of Cursor user traffic, and we’re speaking with the OpenAI team to resolve this. Cursor was one of the very first users of OpenAI, we’ve worked closely with their team for years, and we’ve trusted their platform to be neutral infrastructure for our business,” Truell wrote.
OpenAI cast the move as a matter of trust. “We are making this choice because we cannot be confident that SpaceX will use our technology within our terms of service, based on our experience with Elon Musk’s companies violating contracts,” the company said in its announcement. Cursor and OpenAI did not immediately respond to CNBC’s requests for comment.
Musk responded on X Saturday, writing: “I couldn’t care less. Scam Altman and Greg Stockman are utterly untrustworthy.” He repeated a longstanding claim that OpenAI “stole an open source nonprofit,” an accusation he has also made in court, saying the company is “stealing a charity.”
A Rivalry a Decade in the Making
Musk co-founded OpenAI as a nonprofit research lab in 2015 and helped fund it in its early years. He left the board in 2018 after disputes over hiring talent away from the company, halting promised donations, and clashing with other board members. After his exit, OpenAI released ChatGPT, partnered with Microsoft, restructured into a for-profit company under a nonprofit parent, and raised substantial funding. Musk sued OpenAI, along with Sam Altman and Greg Brockman, in 2024. He lost the case earlier this year and has said he will appeal.
Cursor’s acquisition is the latest in a series of deals tied to Musk’s companies. SpaceX had already acquired both X and xAI in February, before going public in June.
Industry Backdrop
OpenAI is reportedly preparing its own public offering for next year. Rival Anthropic has held preliminary talks with bankers about a possible IPO this year, with a valuation that could reach as high as $2 trillion, according to prior CNBC reporting.
Anthropic has cut off developer access before, blocking the coding tool Windsurf from using its Claude models last June. But its relationship with Cursor is heading a different direction: Anthropic is now partnering with SpaceX and renting compute capacity from Musk’s company, and it plans to keep supplying Cursor with Claude models even under new ownership.
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