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promptfoo

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Promptfoo is an open-source CLI tool, co-founded by Ian Webster and Michael D'Angelo, for testing, evaluating, and red-teaming LLM applications, letting developers define test cases and run them against more than 50 model providers. Used by over 350,000 developers, the tool remains open source under the MIT license even after OpenAI announced its acquisition of the Promptfoo team in March 2026.

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Promptfoo(github.com/promptfoo/promptfoo)

Open-source LLM testing tool with declarative test cases, model comparison, red-teaming, and CI integration.

Developer ToolsOpen SourceLLM Eval★ 25.6kMITbuilt by promptfooIndexed 3mo ago