Letta

Free

Build AI with advanced memory that can learn and self-improve over time.

FreeFree tier

Type

Open Source

Visit Website GitHub (38 stars)

About Letta

Letta (formerly MemGPT) is an open-source platform for building stateful AI agents with advanced memory that can learn and self-improve over time. It provides two main components: the Letta Agent, which runs locally in the terminal, via a desktop app, or through channels like Slack; and the Letta Agent SDK (TypeScript), which allows developers to build stateful agents into their own applications. Letta is fully model-agnostic, supports skills and subagents for continual learning, and can run agents on the cloud (Constellation), locally, or against a self-hosted App Server. The CLI tool, installed via npm, enables launching agents that assist with coding and other tasks. Note that active development has moved to the Letta Agent repository, and the API server is now hosted via the App Server.

Key Features

Stateful agents with advanced memory for learning and self-improvement over time

Runs locally via terminal, desktop app, or channels like Slack

CLI tool for coding assistance (requires Node.js 22.19+)

Supports skills and subagents for continual learning

Model-agnostic, compatible with Anthropic, OpenAI, zAI, and others

TypeScript SDK for building stateful agents into applications

Deployment options: cloud (Constellation), local, or self-hosted App Server

Bundles pre-built skills/subagents for advanced memory

Pros & Cons

Pros

Open source with an active GitHub community (23.9k stars)
Advanced memory capabilities allow agents to learn and adapt
Model-agnostic, giving flexibility to choose LLM providers
Multiple deployment options: local, cloud, self-hosted
Supports skills and subagents for modular, scalable agent behavior
CLI tool provides easy entry point for developers

Cons

Active development has moved to a separate repository (Letta Agent), potentially confusing for users
CLI tool requires Node.js 22.19+, which may limit some users
Cloud features require a Letta API key (no explicit pricing details)
Documentation may be fragmented between legacy and new repos

Best For

Building AI assistants with persistent memory for long-term interactionsCoding assistance via terminal-based agentsCreating Slack bots that learn from conversationsDeveloping autonomous agents that improve over timeIntegrating stateful AI into custom applications using the SDKPrototyping continual learning AI systems

FAQ

What is Letta?

Letta (formerly MemGPT) is an open-source platform for building stateful AI agents with advanced memory that can learn and self-improve over time.

How can I get started with Letta?

You can get started in the CLI by installing the Letta Code CLI tool via npm and running 'letta' in your terminal. Alternatively, use the Letta Agent SDK (TypeScript) to build agents into your applications.

What deployment options are available?

Letta agents can run locally, via the desktop app, on channels like Slack, on the cloud (Constellation), or against a self-hosted App Server.

Is Letta model-agnostic?

Yes, Letta is fully model-agnostic and works with various LLMs including Anthropic, OpenAI, and zAI.