Letta: the MemGPT successor for agents that remember
Letta, formerly MemGPT, builds stateful AI agents: they keep memory, identity and skills from one conversation to the next, and can rewrite them on their own. Today the project runs through Letta Code, an open-source TypeScript tool, alongside a cloud offering.
Data as of October 22, 2026
Key figures
| Developer | Letta (anciennement MemGPT) |
|---|---|
| Type | Code |
| Languages | TypeScript |
| Open source | Yes |
| License | Apache-2.0 |
| First release | October 2023 |
| Suggested level | Intermediate |
| Use cases | chatbot, coding, automation, multi-agent |
| Self-hostable | Yes |
| Business model | Freemium |
| Cloud offering | Yes |
| Multi-agent | Yes |
| MCP support | Yes |
| Bring your own model | Yes |
| Official site | Official site · Documentation · Repository |
GitHub
| Repository | letta-ai/letta-code |
|---|---|
| GitHub stars | 3,681 |
| Forks | 443 |
| Latest code activity | October 22, 2026 |
| Latest release | v0.34.20: chore: bump version to 0.34.20 (#5204) (October 21, 2026) |
GitHub activity checked on October 22, 2026.
Memory as the starting point
A language model forgets anything that falls outside its context window, the amount of text it can read at once. MemGPT proposed handling that limit the way an operating system handles memory: the agent itself decides what to keep, file away or recall. Letta carries that idea forward. Its agents have “memory blocks” they rewrite to improve, skills they learn, and “dreaming” phases during which they reorganize what they know. It is a textbook case of agent memory taken a long way.
What Letta offers today
The project changed a lot in 2026. Its core is now Letta Code, an open-source agent “harness”: a command-line interface, access to the same agent from the browser (chat.letta.com, including on mobile) or from Slack, Telegram and Discord, subagents, scheduled tasks, permission rules and hooks for automation. All of the agent’s context is tracked with git. For developers, the Letta Agent SDK, in TypeScript, lets you create an agent once, resume it from anywhere and connect it to MCP servers.
Getting started
Install it with npm (npm install -g @letta-ai/letta-code) or, if you prefer, with the Python tools uv or pipx, which bundle Node.js. Then run the letta command in your project folder; a tutorial agent helps you find your way around. The /connect command plugs in your own keys (OpenAI, Anthropic and others), and /model switches models.
Strengths, limits and alternatives
Strengths. A research-backed approach to memory, persistent agents reachable from several interfaces, an Apache 2.0 license, model choice and the option to self-host.
Limits. The move from the original Python server to Letta Code makes part of the older documentation and tutorials obsolete; the old AgentFile export format has also been removed. Letta Cloud is the default on first launch, and several advanced features require an account. Automatic background reflection is also disabled by default on native Windows.
Alternatives. For a Python framework with memory stored in your own database, see Agno. For an agent harness close to Claude Code, try the Claude Agent SDK; for an open-source command-line agent, Goose.
Official site: letta.com.
Frameworks of the same type
- Agno · multi-agent, workflows, RAG
- Amazon Bedrock Agents / AgentCore · multi-agent, RAG, workflows
- Atomic Agents · workflows, chatbot, automation
- CAMEL · multi-agent, data, automation
- Claude Agent SDK · coding, automation, workflows
- CrewAI · multi-agent, automation, workflows
Frequently asked questions
Are Letta and MemGPT the same project?
Yes. Letta is the new name of MemGPT, a project that started with a research paper published in October 2023; memgpt.ai now redirects to letta.com. The team says it created MemGPT and the work on sleep-time compute, now called dreaming.
Does the old Python Letta server still exist?
It is no longer actively developed: the original repository states that the Letta V1 API server is archived, with its releases kept available for reproducibility. Active code now lives in Letta Code, written in TypeScript.
How much does Letta cost?
Letta Code is open source under the Apache 2.0 license. As of October 22, 2026, the Free cloud plan costs nothing (up to three stateful agents, with your own API keys), Pro is 20 dollars a month, the API Plan 20 dollars a month plus usage, Teams Pro 20 dollars per seat per month, and Enterprise is quoted on request.
Can I use Letta without the vendor's cloud?
Yes. On first launch you can choose to proceed locally instead of signing in to Letta Cloud, and an App Server lets you host your agents on your own machine. Some features, such as remote computers and secrets shared across machines, do require a Letta account.
Data sources
- github.com
- github.com
- docs.letta.com
- docs.letta.com
- arxiv.org
- GitHub — Repository metadata: GitHub
Data as of October 22, 2026
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