OpenAI signaled late Friday that it would begin winding down model access on Cursor, the AI coding platform now owned by Elon Musk's SpaceX. SpaceX closed the $60 billion purchase on Aug. 14, and OpenAI's proposed cutoff is Nov. 12.
OpenAI's reason: It is not confident SpaceX will stay within its terms of service, citing past contract violations by Musk's companies.
Cursor CEO Michael Truell said on X that OpenAI models handle about 5% of Cursor's user traffic and that talks are underway. He also said Cursor was one of OpenAI's earliest users and had long treated OpenAI as neutral infrastructure.
OpenAI said it will not provide future models to Cursor during the wind-down. Cursor and OpenAI did not respond to CNBC's requests for comment.
This newest clash sits on top of a long-running fight between Musk and OpenAI's leaders. Musk co-founded OpenAI in 2015, left its board in 2018, and sued OpenAI, CEO Sam Altman, and President Greg Brockman in 2024. He lost earlier this year and has vowed to appeal.
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On Saturday, Musk posted on X that he "couldn't care less," used an expletive about his critics, and again said OpenAI stole "an open source nonprofit."
Before SpaceX bought Cursor, it had already acquired Musk's X and xAI in February and had gone public in June.
OpenAI's move is not the first of its kind. Anthropic has reached a deal with SpaceX to lease compute capacity from Musk's company. Last June, Anthropic blocked Windsurf from accessing its Claude AI models.
Anthropic co-founder and executive Tom Brown wrote on X that Cursor has been a trusted partner since Sonnet 3.5, and Anthropic will increase compute to keep support Claude models in Cursor. That post drew pushback from Replit CEO Amjad Masad and Docker executive Matt Velloso.
The backdrop also includes a hot "vibe coding" market. OpenAI is likely to launch an IPO next year, while Anthropic has held preliminary banker talks ahead of a possible IPO that could value it at up to $2 trillion, CNBC previously reported.