Create LLM graders and run evals in JavaScript with one file
Hi HN! Run it: OPENROUTER_API_KEY="sk" npx bff-eval --demo We built a tool to help people take LLM outputs and easily grade them / eval them to know how good an assistant response is. We've built a number of LLM apps, and while we could ship decent tech demos, we were disappointed with how they'd perform over time. We worked with a few companies who had the same problem, and found out scientifically building prompts and evals is far from a solved problem... writing these things feels more like directing a play than coding. Inspired by Anthropic's constitutional ai concepts, and amazing…
Create LLM graders and run evals in JavaScript with one file launched on June 5, 2025 with 28 votes, #644 of 7,999 launches that month and more than 90% of that year's launches. The site was not reachable when checked in September 2026.
In plain words
bff-eval is a JavaScript tool that lets developers create LLM graders and run evaluations from a single file. It helps users assess the quality of AI assistant responses by grading outputs against specified criteria. The tool addresses performance degradation in LLM applications over time by enabling scientific prompt building and evaluation through structured debugging techniques, inspired by constitutional AI concepts. Users can test multiple models against datasets and use actual metrics to improve response quality without retraining models.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
Hi HN! Run it: OPENROUTER_API_KEY="sk" npx bff-eval --demo We built a tool to help people take LLM outputs and easily grade them / eval them to know how good an assistant response is. We've built a number of LLM apps, and while we could ship decent tech demos, we were disappointed with how they'd perform over…
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