Promptfoo tests AI systems for about a quarter of the Fortune 500. OpenAI is buying the startup to put automated security testing inside Frontier, its enterprise platform for AI agents. The deal makes agent safety a product feature.
OpenAI plans to announce Monday it will integrate Promptfoo into Frontier, a platform it introduced in February for building and managing “AI coworkers” with permissions and guardrails. Terms were not disclosed. Promptfoo makes open-source tooling for AI security evaluation and red-teaming, where teams attack their own systems to find weaknesses before release.
We’re acquiring Promptfoo.
— OpenAI (@OpenAI) March 9, 2026
Their technology will strengthen agentic security testing and evaluation capabilities in OpenAI Frontier. Promptfoo will remain open source under the current license, and we will continue to service and support current customers.…
The timing tracks a broader shift toward agentic workflows. OpenAI and rivals are pushing systems that execute multi-step tasks with limited oversight, which increases the impact of a single bad tool call. Last week OpenAI previewed Codex Security, an agent designed to find and patch vulnerabilities, after similar security tooling surfaced across the sector. The Promptfoo acquisition adds testing at build time, not only monitoring after deployment.
Promptfoo raised an $18.4 million Series A last year led by Insight Partners, with Andreessen Horowitz participating. “OpenAI acquiring Promptfoo signals a clear commitment to making enterprise AI not just powerful, but safe and reliable at scale,” said Ganesh Bell, managing director at Insight Partners. Promptfoo is about two years old and based in San Francisco, and it counts roughly a quarter of Fortune 500 firms as customers.
OpenAI said Frontier will gain automated security testing, red-teaming features, and tools to track test runs and changes over time for risk and compliance needs. The tooling is designed to help organizations prove controls before granting agents broader data access in production. OpenAI said it will keep building Promptfoo’s open-source work while wiring the technology into Frontier. The next catalyst is the Frontier rollout pace and how quickly large buyers require embedded red-teaming before they deploy agents widely.
