Letta vs 
Phidata
Letta vs Phidata compared for 2026 — features, license, ease of use, performance and which one to choose. Stateful agents with long-term memory vs Agents with memory, knowledge and tools.
Updated regularly · curated by OpenSourceAI.tech
Letta vs Phidata at a glance
| Spec | Letta | Phidata |
|---|---|---|
| Category | AI agent framework | AI agent framework |
| Type | Agent runtime (memory) | Agent framework |
| License | Apache-2.0 | MPL-2.0 |
| Runs locally | Self-hosted | Yes |
| Primary language | Python | Python |
| Ease of use | Advanced | Beginner |
| Best for | agents that remember across sessions | agents that need to remember and retrieve |
| GitHub stars | 23.8k | — |
How Letta and Phidata score
| Criterion | Letta | Phidata |
|---|---|---|
| Popularity | 3.5 | n/a |
| Maintenance | 5.0 | n/a |
| Ease of use | 2.5 | 5.0 |
| Privacy | 4.5 | 5.0 |
| License freedom | 5.0 | 3.5 |
Scores are computed automatically from public signals — GitHub stars (popularity), recent commit activity (maintenance), license type (freedom), local-first design (privacy) and onboarding complexity (ease of use). Indicative, not a verdict.
What each one is
Letta
Letta (formerly MemGPT) is a framework and server for building stateful agents with long-term memory that persists across sessions, with a visual agent editor.
- Persistent long-term agent memory
- Server with REST API and visual editor
- Model-agnostic and self-hostable
Phidata
Phidata builds agents that combine memory, a knowledge base and tools, and ships a UI to chat with and inspect them.
- Memory and knowledge built in
- Ships an agent inspection UI
- Simple, readable API
Key differences
Letta is agent runtime (memory), while Phidata is agent framework. Their licenses differ (Apache-2.0 vs MPL-2.0), which matters if you ship a commercial product. Letta leans more advanced-friendly, whereas Phidata is more suited to beginner users. They also differ in how they run (Self-hosted vs Yes). In short, Letta fits agents that remember across sessions, and Phidata fits agents that need to remember and retrieve.
Which should you choose?
Choose Letta for agents that remember across sessions. Choose Phidata for agents that need to remember and retrieve.
There is rarely one winner — many setups use both. The right pick depends on your hardware, your team's skills, and whether you value simplicity or control.
Frequently asked questions
Is Letta or Phidata easier to use?
Phidata is generally the easier of the two to get started with, while Letta rewards more setup with more control.
Are Letta and Phidata free?
Letta is free and open source (Apache-2.0), and Phidata is free and open source (MPL-2.0). Neither charges for the core software.
Can I run Letta and Phidata locally?
Letta: self-hosted · Phidata: yes. Both can be used without sending your data to a third-party cloud where their setup allows.
Letta vs Phidata — which should I pick in 2026?
Choose Letta for agents that remember across sessions. Choose Phidata for agents that need to remember and retrieve.
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