Anthropic blocked OpenAI from using its Claude AI models because OpenAI engineers used Claude’s coding tools in ways that violated Anthropic’s terms of service. OpenAI tested Claude’s coding and safety features for preparing GPT-5, which Anthropic says breaches rules against using Claude to build or improve competing AI models. This is part of growing competition and strict restrictions among AI companies.
Additionally, many developers using Claude Code have faced wrongful violation warnings due to aggressive automatic detection systems mistakenly flagging normal activities like medical research or coding questions. These false alerts cause frustration and show the challenge of balancing security with user access.
In short, Anthropic cut OpenAI’s API access to Claude due to improper use for competition, while ordinary developers also suffer from strict and sometimes faulty rule enforcement on the platform.
