OpenAI-Promptfoo Acquisition: Product, Team and Open-Source Plan

What OpenAI bought

Promptfoo announced on March 9, 2026 that it was joining OpenAI, subject to customary closing conditions. Promptfoo is an open source red teaming, static scanning and evaluation suite for LLM applications, founded in 2024 by CEO Ian Webster and CTO Michael D'Angelo. At the time of the deal it counted more than 350,000 developers, 130,000 monthly active users and adoption at more than a quarter of the Fortune 500. [1]

Neither company disclosed a purchase price. Promptfoo had raised 23 million dollars in funding and was valued at 86 million dollars after a July 2025 round, according to PitchBook data cited in coverage of the deal. [3]

The 23 person Promptfoo team was set to continue serving existing customers through the transition. The founders described the move as access to OpenAI's resources and to research at the model and inference layers, calling it the fastest path to their existing mission of helping teams deploy AI securely. [1]

The open source project keeps its license

Promptfoo's announcement said its open source suite would keep operating, stay actively maintained, and continue supporting a wide range of model providers rather than narrowing to OpenAI's own models. As of this check, Promptfoo's GitHub repository confirms the project remains MIT licensed and describes itself as now part of OpenAI. [1][4]

OpenAI's stated plan is to fold Promptfoo's technology into the model and infrastructure layers underneath Frontier, the enterprise platform it launched in February 2026 for building and managing AI agents, so that vulnerabilities in agent workflows surface earlier in development. [3]

A safety tool acquired by the company it tested

Atlas interpretation: Promptfoo's product exists to probe AI systems, including agents, for the kind of failures a vendor would rather not ship: prompt injection, data leakage, unsafe tool use. Folding that tool into the vendor whose agent platform it might otherwise be used to test does not make the tool worse at its job, but it does mean the party most exposed by a finding is now also the party deciding how the tool evolves and who gets early access to what it finds. [3]

Neither Promptfoo's announcement nor the reporting on the deal addresses that tension directly. Both frame the acquisition as a resourcing story, more engineering and research access for a small team, rather than as a change in who Promptfoo answers to when it finds something. [1][3]