head to head · open source
ponytail vs Letta
ponytail has 141,230 GitHub stars, 7,572 forks, 270 open issues and last shipped 4 days ago. Letta has 3,366 stars, 411 forks, 347 open issues and last shipped yesterday. ponytail leads on adoption by 4,096% (141,230 vs 3,366 stars). ponytail is written in JavaScript under MIT; Letta is written in TypeScript under Apache-2.0. ponytail has attracted 5% as many forks as stars, Letta 12%. Letta was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (claude), 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 | Letta | |
|---|---|---|
| GitHub stars | ★ 141K | ★ 3.4K |
| License | MIT | Apache-2.0 |
| Written in | JavaScript | TypeScript |
| Last push | 2026-09-14 | 2026-09-17 |
| Forks | ⑂ 7.6K | ⑂ 411 |
| 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 Letta if
- You want the Letta feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches TypeScript
- You evaluated both and Letta 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 Letta
Letta Code is an open source TypeScript harness under Apache 2.0 for stateful AI agents. It lives in the AI & Machine Learning / AI Development Platforms ecosystem. It gives agents memory, identity, and a sense of experience over time. It targets agents that behave more like people than tools.
read the full Letta overview →
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Frequently asked questions
Is ponytail or Letta more popular?
ponytail has 141,230 GitHub stars and Letta has 3,366. ponytail has the larger community by that measure.
Are ponytail and Letta free?
Both are open source. ponytail is licensed under MIT and Letta under Apache-2.0. Neither carries a licence fee.
What is the difference between ponytail and Letta?
ponytail is written in JavaScript and Letta 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 Letta?
Choose ponytail if you want the larger community (141,230 stars) or its MIT licence terms. Choose Letta if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.