head to head · open source
ponytail vs Foundry
ponytail has 182,779 GitHub stars, 10,094 forks, 270 open issues and last shipped 5 days ago. Foundry has 893 stars, 136 forks, 5 open issues and last shipped 7 days ago. ponytail leads on adoption by 20,368% (182,779 vs 893 stars). ponytail is written in JavaScript under MIT; Foundry is written in Python under Apache-2.0. ponytail has attracted 6% as many forks as stars, Foundry 15%. ponytail was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (ai-agents, developer-tools), 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 | Foundry | |
|---|---|---|
| GitHub stars | ★ 183K | ★ 893 |
| License | MIT | Apache-2.0 |
| Written in | JavaScript | Python |
| Last push | 2026-10-29 | 2026-10-27 |
| Forks | ⑂ 10K | ⑂ 136 |
| 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 Foundry if
- You want the Foundry feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Python
- You evaluated both and Foundry 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 Foundry
Promptise Foundry The first full stack Agentic Engineering framework. Build agents and the tools they use. Design how they reason. Run them as autonomous, governed systems. Ship them to real customers — multi tenant, secure, and observable. One framework, not a dozen libraries. Website · Documentation · Quick Start · Blog · Discussions What Promptise is Promptise is one framework for the whole job of building with AI agents — the agents, the tools they use, the reasoning behind them, the runtime that keeps them running, and the security and governance to put them in front of customers. Not a single feature, but…
read the full Foundry overview →
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Frequently asked questions
Is ponytail or Foundry more popular?
ponytail has 182,779 GitHub stars and Foundry has 893. ponytail has the larger community by that measure.
Are ponytail and Foundry free?
Both are open source. ponytail is licensed under MIT and Foundry under Apache-2.0. Neither carries a licence fee.
What is the difference between ponytail and Foundry?
ponytail is written in JavaScript and Foundry in Python. 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 Foundry?
Choose ponytail if you want the larger community (182,779 stars) or its MIT licence terms. Choose Foundry if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.