OpenAI Rival Anthropic Blocks Windsurf from Using Claude 4 Models

Anthropic released its latest Claude 4 models — Claude Opus 4 and Claude Sonnet 4 — but Windsurf users were not given immediate access. Varun Mohan, co-founder of Windsurf, said in a post on X, “Unfortunately, Anthropic did not provide our users direct access to Claude Sonnet 4 and Opus 4 on day one.”

However, he added that the company has made Gemini 2.5 Pro work significantly better in Windsurf, which is now a recommended model.

Meanwhile, as a workaround, Windsurf has enabled bring-your-own-key (BYOK) support for Claude Sonnet 4 and Opus 4. This option is now available across all individual plans, including Free and Pro. 

Notably, Windsurf was recently acquired by OpenAI for $3 billion. 

“We are actively working to find capacity elsewhere so we can continue to provide the most versatile and powerful AI assistance platform, period,” Mohan added.

Anthropic positioned Claude Opus 4 as its most capable model, stating that it “delivers sustained performance on long-running tasks that require focused effort and thousands of steps.” 

Claude Opus 4 scored 72.5% on SWE-bench and 43.2% on Terminal-bench. Sonnet 4, a follow-up to version 3.7, also scored 72.7% on SWE-bench and is available to both free and paid users.

The Claude 4 models are accessible via the Anthropic API, Amazon Bedrock, and Google Cloud’s Vertex AI and are available on coding platforms like Cursor, Lovable and Replit. 

The models support extended reasoning, parallel tool use, and the extraction and storage of key information from developer files.

Meanwhile, GitHub plans to integrate Sonnet 4 into a future version of GitHub Copilot. According to GitHub, the model “soars in agentic scenarios.” 

Companies such as Sourcegraph, Manus, iGent, and Augment Code also reported improvements in code editing and problem-solving with Sonnet 4.

To support development workflows, Anthropic also launched Claude Code as a generally available tool. It integrates into IDEs like VS Code and JetBrains, supports GitHub Actions, and allows developers to tag Claude in pull requests for direct assistance.