An OpenAI spokesperson said the API access allowed for industry-standard benchmarking and safety improvements.

Reportedly, Anthropic has restricted OpenAI from accessing the Claude API after noticing an apparent breach of the terms of use. Specifically, it found OpenAI engineers using Claude Code ahead of the GPT-5 release.

As reported by Wired, multiple sources claim that OpenAI has been cut off from Anthropic’s APIs. Allegedly, OpenAI was using Anthropic’s Claude Code to assist in creating and testing OpenAI’s upcoming GPT-5, which is due to release in August .