Windsurf, the popular vibe coding startup that’s reportedly being acquired by OpenAI, said Anthropic significantly reduced its first-party access to the highly popular AI models Claude 3.7 Sonnet and Claude 3.5 Sonnet.

Windsurf CEO Varun Mohan said in a post on X that Anthropic gave Windsurf little notice for this change, and the startup now has to find other third-party compute providers to run Claude AI models on its platform.

“We have been very clear to Anthropic that this is not our desire – we wanted to pay them for the full capacity,” said Mohan on X. “We are disappointed by this decision and short notice.”

In a blog post, Windsurf said this it has some capacity with third-party inference providers, but not enough, so this change may create short-term availability issues for Windsurf users trying to access Claude.

The decision comes just a few weeks after Anthropic seemed to pass over Windsurf during the launch of Claude 4, the company’s new family of models, which offer industry leading performance on software engineering tasks. Anthropic gave several popular vibe coding apps — including Anysphere’s Cursor, Cognition’s Devin, and Microsoft’s GitHub Copilot — immediate access to run Claude Sonnet 4 and Claude Opus 4. Those apps started supporting the new Claude 4 models on launch day.

Windsurf said at the time it did not receive direct access from Anthropic to run Claude 4 on its platform, and still hasn’t — forcing the company to rely on a workaround that’s more expensive and complicated for developer to access Claude. Anthropic’s AI models have become a favorite among developers, and in the past, Anthropic has worked with Windsurf to power its vibe coding tools.

The AI-assisted coding sector, also know as vibe coding, has heated up in recent months. OpenAI reportedly closed on a deal to acquire Windsurf in April. At the same time, Anthropic has invested more in its own AI-coding applications. In February, Anthropic launched its own AI coding application, Claude Code, and in May, the startup held its first Code with Claude developer conference.

“We’re prioritizing capacity for sustainable partnerships that allow us to effectively serve the broader developer community,” said Anthropic spokesperson Steve Mnich in an email to TechCrunch on Tuesday, noting that it’s still possible to access Claude on Windsurf via an API key. “Developers can also access Claude through our direct API integration, our partner ecosystem, and other development tools.”

Windsurf has grown quickly this year, reaching $100 million ARR in April, in an attempt to catch up with more popular AI coding tools such as Cursor and GitHub Copilot. However, Windsurf’s limited access to Anthropic’s models may be stunting its growth.

Several Windsurf users that spoke with TechCrunch were frustrated by the lack of direct access to Anthropic’s best AI coding models.

Ronald Mannak, a startup founder that specializes in Apple’s programming language, Swift, told TechCrunch that Claude 4 represented a significant jump in capabilities for his workloads. While Mannak has been a Windsurf customer since late 2024, he’s switched to using Cursor in recent weeks so that he can vibe code more easily with Claude 4.

As a short-term solution to support Claude 4, Windsurf allows users to connect their Anthropic API keys to their Windsurf accounts. However, developers have noted that this “bring your own key” solution is more expensive and complicated than if Windsurf provided the models itself.

When it comes to vibe coders, optionality is the name of the game. Every few months, OpenAI, Google, and Anthropic release new AI models that seem to outperform the industry on coding tasks. Because of that, it benefits vibe coding startups to support AI models from all the leading developers.

Windsurf spokesperson Payal Patel tells TechCrunch via email that the company has always believed in providing optionality for users. In this case, it seems Anthropic has made that a bit more challenging.