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Prompt Eval turns "this prompt looks better" into a number you can defend.
Run your prompt across a dataset of test cases and get a scored report: average score, pass rate, and per-case reasoning that explains exactly why each case passed or failed. Three grader types (deterministic regex/JSON/Python, LLM-as-judge, and reference-based) so you're not trusting a single black box.
Compare versions side by side to catch regressions before your users do. Bring your own test cases or generate them in seconds. A built-in Learn hub covers the prompting techniques that actually move scores.
One real example: a prompt scored 2.32/10 on a test set. Two technique changes later, 7.86/10. Same task, measured, not guessed.
20 free credits to start, no card required, then pay-as-you-go.