head to head · open source
ponytail vs Foundry
ponytail has 141,230 GitHub stars, 7,572 forks, 270 open issues and last shipped 4 days ago. Foundry has 872 stars, 129 forks, 5 open issues and last shipped 29 days ago. ponytail leads on adoption by 16,096% (141,230 vs 872 stars). ponytail is written in JavaScript under MIT; Foundry is written in Python under Apache-2.0. ponytail has attracted 5% 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 | ★ 141K | ★ 872 |
| License | MIT | Apache-2.0 |
| Written in | JavaScript | Python |
| Last push | 2026-09-14 | 2026-08-20 |
| Forks | ⑂ 7.6K | ⑂ 129 |
| 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 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 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 Foundry
Foundry is a Python, Apache 2.0 licensed agentic engineering framework from Promptise that gives developers one install for building AI agents, the tools they call, the reasoning they follow, and the governed runtime that serves them to customers.
read the full Foundry overview →
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Frequently asked questions
Is ponytail or Foundry more popular?
ponytail has 141,230 GitHub stars and Foundry has 872. 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 (141,230 stars) or its MIT licence terms. Choose Foundry if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.