Anthropic says OpenAI engineers using Claude Code ahead of GPT-5 launch

Anthropic says it has revoked OpenAI’s access to the Claude API after ChatGPT’s engineers were found using Claude’s coding tools.

Claude Code is better than any other coding tool in the AI coding industry, also known as “Vibe coding.”

With Claude, you can create web apps from scratch, and it’s also pretty efficient with infra-related work.

Not just vibe coders who don’t know how to code use Claude, but also professional engineers.

In fact, Claude Code is also used in Claude’s development at Anthropic.

Anthropic offers API access to Claude, which means OpenAI could also access it.

But on Friday, Anthropic confirmed that it revoked OpenAI’s access to Claude Code after the company was found using its coding tools ahead of the GPT-5 launch.

“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,” Anthropic spokesperson Christopher Nulty noted in a statement to Wired.

It’s unclear how OpenAI engineers were using Claude Code, but it’s possible it was used to improve GPT-5’s coding capabilities.

GPT-5 is expected to launch next week with “auto” and reasoning modes.