Anthropic will not follow OpenAI in cutting off Cursor over SpaceX deal

Tom Brown, co-founder of Anthropic, has announced that the company will continue to supply its Claude models to Cursor while adding more compute behind them. 

He made the statement within 24 hours of OpenAI informing SpaceX (NASDAQ: SPCX) of its decision to cut Cursor off, in response to Elon Musk’s $60 billion purchase of Cursor’s parent company. 

Two AI labs, two different responses

OpenAI announced plans to stop supplying its models to Cursor on August 28, with hopes to end the contractual relationship by November 12, 2026. The company claims it is doing this reluctantly, but Musk’s purchase of the company has left it without a choice. 

The Altman-led firm claimed Musk-owned companies have a habit of violating contracts, citing Twitter’s violations of terms, which Musk himself admitted to under oath.

Anthropic did the exact opposite, saying “Cursor has been a trusted partner of Anthropic since Sonnet 3.5,” according to Brown. He went on to add that Anthropic would “continue to increase compute to support Claude models in Cursor.” 

The $60 billion purchase that kicked things off

SpaceX purchased Anysphere in an all-stock transaction in June and closed on August 14. This is based on an 8-K filing with the SEC. The filing places Cursor’s value at $60 billion with a total of 389.3 million shares of SpaceX Class A stock. The deal is one of the largest startup acquisitions as of today.  

The change in ownership gives OpenAI a legal pathway to back out of its contract with Cursor. The agreement with Cursor had a clause that allowed cancellation of the agreement after a change in ownership, within a specific time frame.  

OpenAI chose to time the cancellation on the latest date possible, per the agreement. OpenAI also based its decision on Astra, an upcoming model it claims ups the ante on who can access its systems or not. 

Musk shrugs it off, and Cursor downplays the loss

Musk gave a blunt response, “I couldn’t care less,” before going on to call OpenAI’s Sam Altman and president Greg Brockman untrustworthy and reiterating his claim that they “stole an open source nonprofit.” 

This episode is the latest in the long-running feud between Musk and OpenAI. Earlier this year, Musk sued OpenAI for $150 billion, but a federal jury dismissed the case as it had exceeded the statute of limitations.

Cursor is not losing sleep over OpenAI’s actions. Co-founder Michael Truell, who is now a SpaceX executive, said in an X post that OpenAI’s models make up just 5% of Cursor’s traffic while they remain in talks to find a resolution. 

Nonetheless, OpenAI’s departure may truncate Cursor’s pitch to developers as a one-stop shop for any leading AI model available.

Anthropic has set the standard before

Anthropic choosing to stay with Cursor rather than cut off ties is a notable one, considering its antecedents. 

In January, Anthropic ditched xAI when its staff used Claude internally via Cursor. The company also cut off OpenAI from its systems just before the launch of GPT-5, saying OpenAI was a direct violation of our terms of service.” This time around, Anthropic is staying put.

The different moves by two leading AI labs split the market into camps, as access to top AI models has become an arms race. For developers, this only means fewer OpenAI options in one famous tool, Cursor, and the realization that you cannot just access any AI model you want anymore. 

Don’t just read crypto news. Understand it. Subscribe to our newsletter. It's free.