May 07, 2026
Prompt engineering is often a game of "trial and error." Promptfoo turns this into a systematic engineering discipline by allowing you to test your prompts against a comprehensive list of test cases, just like unit tests for code.
Promptfoo runs from the command line, allowing you to quickly compare the outputs of multiple prompts or multiple models (e.g., GPT-4 vs. Claude 3) side-by-side. It provides a visual matrix that makes it obvious where a prompt is failing or where one model outperforms another.
Beyond visual inspection, Promptfoo supports automated assertions. You can check for the presence of specific keywords, use LLMs to grade the "helpfulness" of the response, or even check for security vulnerabilities, ensuring that your AI responses always meet your quality standards.