The Antibody

OpenAI acquired Promptfoo — the open-source AI red-teaming tool used by a quarter of the Fortune 500. It is the latest move in a pattern where every major AI platform company is building its own security layer, absorbing a thirty-five-billion-dollar market the way Windows absorbed antivirus. OpenAI announced on March 9 that it will acquire Promptfoo — the open-source AI red-teaming tool used by more than a quarter of the Fortune 500. The acquisition will embed Promptfoo's automated security testing directly into Frontier, OpenAI's enterprise agent platform launched five weeks earlier. The deal makes OpenAI the builder, the deployer, and the tester of its own AI agents. It is the latest — and arguably the clearest — instance of a pattern now visible across every major AI platform: the organism is building its own immune system. The Acquisition Promptfoo was founded by Ian Webster, a former Discord AI engineering lead who started building red-teaming tooling on nights and weekends in 202