head to head · open source
Mem0 vs Letta
Mem0 has 68,288 GitHub stars, 8,104 forks, 742 open issues and last shipped 4 days ago. Letta has 3,764 stars, 465 forks, 347 open issues and last shipped yesterday. Mem0 leads on adoption by 1,714% (68,288 vs 3,764 stars). Mem0 is written in Python under Apache-2.0; Letta is written in TypeScript under Apache-2.0. Mem0 has attracted 12% 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 (ai), 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
| Mem0 | Letta | |
|---|---|---|
| GitHub stars | ★ 68K | ★ 3.8K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Python | TypeScript |
| Last push | 2026-10-30 | 2026-11-02 |
| Forks | ⑂ 8.1K | ⑂ 465 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Mem0 if
- You weight community size — 68K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Python
- 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 Mem0
Learn more · Join Discord · Demo 📄 Benchmarking Mem0's token efficient memory algorithm → New Memory Algorithm (April 2026) All benchmarks run on the same production representative model stack. Single pass retrieval (one call, no agentic loops) at a top 200 retrieval budget. Scores reflect Mem0's managed platform, which includes proprietary optimizations not available in the open source SDK; open source users should expect directionally similar gains but not identical numbers. What changed: Single pass ADD only extraction one LLM call, no UPDATE/DELETE. Memories accumulate; nothing is overwritten. Agent…
About Letta
Letta Code Letta Code is a stateful agent harness for creating agents that are more like people than tools. Letta Code agents have memory, identity, and a sense of experience over time. They learn and evolve over long horizons through rewriting their own memory, skills, prompts, and even the harness itself (through mods). Letta Code can be used interactively, or to power always on agents that work proactively. Interact with agents through: A local CLI The desktop app for macOS, Windows, and Linux Your browser, including mobile, at chat.letta.com Messaging integrations, including Telegram, Slack, Discord, and…
read the full Letta overview →
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Frequently asked questions
Is Mem0 or Letta more popular?
Mem0 has 68,288 GitHub stars and Letta has 3,764. Mem0 has the larger community by that measure.
Are Mem0 and Letta free?
Both are open source. Mem0 is licensed under Apache-2.0 and Letta under Apache-2.0. Neither carries a licence fee.
What is the difference between Mem0 and Letta?
Mem0 is written in Python 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, Mem0 or Letta?
Choose Mem0 if you want the larger community (68,288 stars) or its Apache-2.0 licence terms. Choose Letta if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.