OpenAI acquired Promptfoo, an artificial intelligence security startup, to protect its enterprise platform from online adversaries. The company plans to integrate the technology into OpenAI Frontier to evaluate agentic workflows and perform automated red-teaming. Promptfoo previously raised $23 million and reached an $86 million valuation in July 2025. The startup currently provides open source vulnerability testing tools to more than 25% of Fortune 500 companies.
