head to head · open source
ponytail vs promptfoo
ponytail has 141,230 GitHub stars, 7,572 forks, 270 open issues and last shipped 4 days ago. promptfoo has 25,231 stars, 2,331 forks, 651 open issues and last shipped yesterday. ponytail leads on adoption by 460% (141,230 vs 25,231 stars). ponytail is written in JavaScript under MIT; promptfoo is written in TypeScript under MIT. ponytail has attracted 5% as many forks as stars, promptfoo 9%. 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 | ★ 141K | ★ 25K |
| License | MIT | MIT |
| Written in | JavaScript | TypeScript |
| Last push | 2026-09-14 | 2026-09-17 |
| Forks | ⑂ 7.6K | ⑂ 2.3K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick ponytail if
- You weight community size — 141K 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 is an open source agent skill for JavaScript and LLM based coding tools that makes an AI agent write the minimum working code for a task, and it is built for developers and teams running agents such as Claude Code, Codex, or Cursor against real repositories.
read the full ponytail overview →
About promptfoo
Promptfoo is an open source command line tool and TypeScript library for evaluating and red teaming large language model applications, aimed at developers, AI engineers, and security teams who need measurable evidence that a prompt, agent, or retrieval augmented generation pipeline behaves correctly and safely before it reaches users.
read the full promptfoo overview →
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Frequently asked questions
Is ponytail or promptfoo more popular?
ponytail has 141,230 GitHub stars and promptfoo has 25,231. 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 (141,230 stars) or its MIT licence terms. Choose promptfoo if its feature set, stack or MIT licence fits better. Both are self-hostable.