OpenAI banned from using Claude AI just before GPT-5 launch: Here's why | Mint

Anthropic has revoked OpenAI's access to its AI models on Tuesday for allegedly violating the company's terms of service, according to a Wired report. The news of Anthropic cutting OpenAI's access to Claude comes at a time when the Sam Altman led company is rumored to be releasing its own GPT 5 model soon.

Anthropic spokesperson Christopher Nulty, while confirming the development in a statement to Wired, said, “Claude Code has become the go-to choice for coders everywhere, and so it was no surprise to learn OpenAI's own technical staff were also using our coding tools ahead of the launch of GPT 5.” 

“Unfortunately, this is a direct violation of our terms of service.” he added.

Meanwhile, Nulty stated that Anthropic will “continue to ensure OpenAI has API access for the purposes of benchmarking and safety evaluations as is standard practice across the industry.”

OpenAI was reportedly plugging Claude into its own internal tools using special developer access (APIs), instead of the chat interface, which allowed the ChatGPT maker to run tests to evaluate the rival AI models' capability on tasks like coding and creative writing. OpenAI was also able to check how Claude responded to safety related prompts in categories like CSAM, self harm and defamation.

The results from these tests reportedly helped OpenAI compare the behavior of its own models under similar conditions and make adjustments as needed.

Anthropic's commercial terms of service state that customers are not allowed to use its AI models to “build a competing product or service, including to train competing AI models or resell the Service.”

Notably, this isn't the first time that Anthropic has cut off a competitor's access to its AI model. Earlier in the year, the company had restricted AI coding startup Windsurf from having direct access to its models after reports started emerging that the company was being acquired by OpenAI.

Anthropic's Chief Science Officer Jared Kaplan had then talked about revoking Windsurf's access to Claude, saying, “I think it would be odd for us to be selling Claude to OpenAI.”