head to head · open source
ponytail vs promptfoo
ponytail has 182,779 GitHub stars, 10,094 forks, 270 open issues and last shipped 5 days ago. promptfoo has 26,753 stars, 2,633 forks, 651 open issues and last shipped yesterday. ponytail leads on adoption by 583% (182,779 vs 26,753 stars). ponytail is written in JavaScript under MIT; promptfoo is written in TypeScript under MIT. ponytail has attracted 6% as many forks as stars, promptfoo 10%. promptfoo was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (llm, prompt-engineering), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| ponytail | promptfoo | |
|---|---|---|
| GitHub stars | ★ 183K | ★ 27K |
| License | MIT | MIT |
| Written in | JavaScript | TypeScript |
| Last push | 2026-10-29 | 2026-11-02 |
| Forks | ⑂ 10K | ⑂ 2.6K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick ponytail if
- You weight community size — 183K stars and counting
- You want the MIT license terms
- Your stack matches JavaScript
- You value the larger contributor base for long-term maintenance
pick promptfoo if
- You want the promptfoo feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches TypeScript
- You evaluated both and promptfoo fits your workflow better
About ponytail
Ponytail He says nothing. He writes one line. It works. 54% less code (up to 94%) · 20% cheaper · 27% faster · 100% safe Measured on real Claude Code sessions editing a real open source repo (FastAPI + React), against the same agent with no skill. 54% is the mean across 12 feature tasks (Haiku 4.5, n=4); it reaches 94% where an agent over builds (a date picker) and is near zero where the code is already minimal. ponytail keeps every safety guard while a bare "write one liners" prompt drops one. (The earlier single shot benchmark reported 80 94% as a flat figure; against a fair agentic…
read the full ponytail overview →
About promptfoo
Promptfoo: LLM evals & red teaming promptfoo is a CLI and library for evaluating and red teaming LLM apps. Stop the trial and error approach start shipping secure, reliable AI apps. Website · Getting Started · Red Teaming · Documentation · Discord Promptfoo is now part of OpenAI. Promptfoo remains open source and MIT licensed. Read the company update. Quick Start Requires Node.js =22.22.0 for npm and npx usage. Node.js 24 LTS is recommended; see the runtime support guide. Also available via brew install promptfoo and pip install promptfoo . You can also use npx promptfoo@latest to run any command without…
read the full promptfoo overview →
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Frequently asked questions
Is ponytail or promptfoo more popular?
ponytail has 182,779 GitHub stars and promptfoo has 26,753. ponytail has the larger community by that measure.
Are ponytail and promptfoo free?
Both are open source. ponytail is licensed under MIT and promptfoo under MIT. Neither carries a licence fee.
What is the difference between ponytail and promptfoo?
ponytail is written in JavaScript and promptfoo in TypeScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, ponytail or promptfoo?
Choose ponytail if you want the larger community (182,779 stars) or its MIT licence terms. Choose promptfoo if its feature set, stack or MIT licence fits better. Both are self-hostable.