OpenAI Will Cut Off Cursor's Model Access After SpaceX Acquisition

OpenAI said on Friday that it plans to wind down the contract supplying its models to Cursor, the coding tool now owned by Elon Musk’s SpaceX, with a proposed shutoff date of November 12, 2026. That is the maximum notice OpenAI’s own contract allows, and the company is using every day of it, though it said Cursor may choose an earlier date.

The move lands fourteen days after SpaceX closed its $60 billion acquisition of Cursor’s parent company, Anysphere, and marks a further escalation in the long-running clash between Musk and OpenAI chief executive Sam Altman.

Cursor chief executive Michael Truell, now an executive at SpaceX, posted the company’s response on X the same night.

“We’re sorry to see that OpenAI put out a note saying they plan to block Cursor users from accessing OpenAI models in three months,” he wrote. “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.”

OpenAI announced the decision in a blog post. “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 wrote.

OpenAI said that after Musk acquired Twitter, now X and part of SpaceX, the company broke the terms of its contract with OpenAI, alongside many others. Under oath earlier this year, Musk admitted that xAI had used OpenAI’s models to help train Grok through distillation, violating OpenAI’s terms of service. Those terms, OpenAI noted, are similar to xAI’s own.

“To work with a large partner like SpaceX, we typically rely on custom contracts to ensure compliance with our terms of service and that the integration provides for safety at scale,” the company said, adding that it carries “a new level of accountability” to ensure its upcoming model, Astra, is used in accordance with its terms.

Musk’s reply, posted the following morning, skipped the diplomacy. “I couldn’t care less. Scam Altman and Greg Stockman are utterly untrustworthy,” he wrote, using an expletive to describe the pair, before repeating the claim at the center of his lawsuit against the company, that they “stole an open source nonprofit.”

Anthropic moved within hours. “Cursor has been a trusted partner of Anthropic since Sonnet 3.5,” co-founder Tom Brown wrote on X on Friday night, saying the company will continue to increase compute supporting Claude models in Cursor.

The mechanism here is a change-of-control clause buried in OpenAI’s custom enterprise agreement with Cursor. Clauses like that let one party review or exit a contract once the other company gets bought, and SpaceX’s acquisition of Anysphere tripped it the moment the deal closed on August 14. OpenAI says the agreement gives it a limited window to cancel after a change of control, and it chose to hold the cancellation to the latest date that window allows.

The feud behind the clause is long-running. Musk co-founded OpenAI in 2015 and left its board in 2018 after hiring talent away from the company, cutting off donations he had promised it, and clashing with fellow board members over its direction. He sued OpenAI, Altman, and Greg Brockman in 2024 in a $150 billion suit, arguing the company’s shift from nonprofit to for-profit betrayed its founding mission. A federal jury ruled against him earlier this year, and he has said he will appeal.

This is also not the first time a model provider has cut off a coding tool over its ownership. Anthropic blocked Windsurf’s access to Claude in June 2025 after reports that OpenAI intended to acquire it, and cut OpenClaw off from Claude subscriptions on terms-of-service grounds this month. OpenAI, for its part, ships Codex, a coding agent that competes directly with the product Musk just bought.

Cursor Says OpenAI Is 5% of Its Traffic

Truell did not break down the remaining traffic. Before the acquisition, Cursor drew on Anthropic’s Claude and Google’s Gemini alongside OpenAI models, and it ships its own Composer model. Neither company has published a usage breakdown that settles what 5% of traffic is worth in revenue.

The weekend’s public statements drew their own pushback. Replit chief executive Amjad Masad pointed to Anthropic’s history of cutting off Windsurf when its loyalty post circulated, and Docker executive Mat Velloso replied, “This was a great opportunity to stay quiet.”

If You Use Cursor

OpenAI models keep working inside Cursor until the shutoff, which is November 12 unless Cursor picks an earlier date. After that, using GPT models in Cursor means supplying your own OpenAI API key at standard API rates instead of routing through Cursor’s bundled subscription, or moving to OpenAI’s own IDE extensions, which stay available.

For most users the practical default is to do nothing: Claude, Gemini, and Composer usage is unaffected, and Anthropic says it is adding Claude capacity for Cursor. The thing to watch is whether the talks Truell described produce a new agreement before the deadline. Neither company had announced further discussions as of Saturday, and OpenAI said it worked with Cursor for nearly four years before the acquisition.