Promptfoo is an open-source CLI and library for evaluating and red-teaming applications built on large language models. Teams use it to test prompts, models and RAG pipelines, compare models from different providers side by side, and probe agents for weaknesses such as prompt injection, jailbreaks, PII leaks and insecure tool use. It runs in CI/CD pipelines and installs through npm, Homebrew or pip. According to the project, evaluations run locally, so prompts stay on your own machine. For companies, the website mentions integrations on-premise or in the cloud.
Promptfoo is MIT-licensed, so you can inspect the code and run it yourself. In March 2026 the company announced that it had agreed to be acquired by OpenAI, and says the open-source project will remain open source and maintained. For a European organisation this means the commercial vendor is owned by a non-European AI provider, while local use of the open-source tool does not require sending data to the vendor.