Letta vs 
Agent Zero
Letta vs Agent Zero compared for 2026 — features, license, ease of use, performance and which one to choose. Stateful agents with long-term memory vs A general agent that grows with your prompts.
Updated regularly · curated by OpenSourceAI.tech
Letta vs Agent Zero at a glance
| Spec | Letta | Agent Zero |
|---|---|---|
| Category | AI agent framework | AI agent framework |
| Type | Agent runtime (memory) | Autonomous agent |
| License | Apache-2.0 | MIT |
| Runs locally | Self-hosted | Yes |
| Primary language | Python | Python |
| Ease of use | Advanced | Intermediate |
| Best for | agents that remember across sessions | a hackable personal autonomous agent |
| GitHub stars | 23.8k | — |
How Letta and Agent Zero score
| Criterion | Letta | Agent Zero |
|---|---|---|
| Popularity | 3.5 | n/a |
| Maintenance | 5.0 | n/a |
| Ease of use | 2.5 | 3.5 |
| Privacy | 4.5 | 5.0 |
| License freedom | 5.0 | 5.0 |
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
Agent Zero
Agent Zero is a fully transparent personal agent framework: it writes and executes code in its own Linux environment, spawns sub-agents, and every behavior is a prompt you can change.
- Everything is a prompt — completely customizable
- Executes real code in an isolated environment
- Hierarchical sub-agents keep context clean
Key differences
Letta is agent runtime (memory), while Agent Zero is autonomous agent. Their licenses differ (Apache-2.0 vs MIT), which matters if you ship a commercial product. Letta leans more advanced-friendly, whereas Agent Zero is more suited to intermediate users. They also differ in how they run (Self-hosted vs Yes). In short, Letta fits agents that remember across sessions, and Agent Zero fits a hackable personal autonomous agent.
Which should you choose?
Choose Letta for agents that remember across sessions. Choose Agent Zero for a hackable personal autonomous agent.
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 Agent Zero easier to use?
Agent Zero is generally the easier of the two to get started with, while Letta rewards more setup with more control.
Are Letta and Agent Zero free?
Letta is free and open source (Apache-2.0), and Agent Zero is free and open source (MIT). Neither charges for the core software.
Can I run Letta and Agent Zero locally?
Letta: self-hosted · Agent Zero: yes. Both can be used without sending your data to a third-party cloud where their setup allows.
Letta vs Agent Zero — which should I pick in 2026?
Choose Letta for agents that remember across sessions. Choose Agent Zero for a hackable personal autonomous agent.
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