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Home/Categories/LLMOps & AI Tooling/Letta
icon of Letta

Letta

Open source alternative to Vellum AI, Google Vertex AI Agent Builder and Kore.ai Agent Platform

Build AI agents with persistent memory that remember users, tools, and context across sessions with a self-hosted Apache-2.0 framework.

2.7K starsTypeScriptApache-2.0Active recently
Visit websiteGitHub repo
image of Letta
Contents
  1. 01Who Letta is for
  2. 02The problem it solves
  3. 03How it solves it
  4. 04Strengths and trade-offs
  5. 05Tech stack
  6. 06FAQ
  7. 07Similar open-source tools
TL;DR

Letta is an AI agent memory framework for building stateful agents that remember users, tools, and context across sessions. It replaces stateless prompt chains and basic RAG wrappers for teams that need persistent agent behavior. Apache-2.0 licensed repository.Apache-2.0 · TypeScript · 2.7K stars · Active recently

who it's for

Who Letta is for#

AI teams building personal assistants

Use Letta when an assistant needs to remember preferences, history, and working context across conversations.

Skip if:

A stateless chatbot with fresh retrieval is enough for your use case.

Developers prototyping agent memory

Use Letta to test how memory changes agent behavior before building custom memory infrastructure.

Skip if:

You cannot store user memory because of policy or compliance limits.

the problem

The problem it solves#

Most LLM applications forget context unless developers keep pushing conversation history, summaries, or retrieval results back into the prompt. That creates brittle behavior and makes agents feel inconsistent across sessions.

Long-running agents need memory as a managed product concern. Teams need to decide what the agent can remember, update, retrieve, and expose instead of treating memory as an accidental prompt side effect.

how Letta solves it

How it solves it#

Persistent agent memory

Letta focuses on agents that retain and update memory across sessions, helping them behave consistently over time.

Framework for stateful agents

Developers can build agent behavior around memory, tools, and context rather than a single stateless model call.

LLMOps-oriented design

The project fits AI engineering workflows where memory, observability, and control matter for production agent behavior.

strengths · trade-offs

Strengths and trade-offs#

Strengths

  • Treats memory as core infrastructureLetta is useful when agent memory needs explicit management instead of hidden prompt tricks.
  • Better fit for long-running agentsPersistent memory helps assistants, copilots, and workflow agents carry useful context between sessions.

Trade-offs

  • -Memory needs governancePersistent memory can store sensitive or stale information. Teams need clear retention, editing, and deletion policies.
tech stack · detected from GitHub

What it's built on#

Languages
JavaScriptTypeScript
Frameworks
React
frequently asked

FAQ#

What is Letta used for?

Letta is used to build AI agents with persistent memory and stateful behavior across sessions.

Does Letta replace RAG?

Letta does not simply replace RAG. It focuses on agent memory, which can work alongside retrieval when agents need both remembered context and external knowledge.

Who should use Letta?

Letta is best for AI teams building assistants or agents where long-term context changes the product experience.

also worth a look

Similar open-source tools#

OpenMolt

OpenMolt

Build scoped TypeScript AI agents with OpenMolt.dev

32TypeScriptMIT
Evolver

Evolver

Self-evolution engine that turns prompt tweaks into assets

8.5KJavaScriptGPL-3.0
Caveman

Caveman

Token-slashing caveman-speak for cheaper, faster AI code.

77.3KJavaScriptMIT
Skills Manager

Skills Manager

Universal skills manager for Claude Code and AI coding agents

57HTMLMIT
AI-Flow

AI-Flow

Visually chain AI models and APIs into automated pipelines

284TypeScriptMIT
Botpress

Botpress

Visual chatbot builder with LLM integration and live deployment

22.6KJavaScriptMIT

Repository

Stars
2.7K
Forks
303
License
Apache-2.0
Latest
v0.27.8
Last commit
36 days ago
Last verified
Jun 12, 2026
Repo
letta-ai/letta-code ↗

Additional details

Language
TypeScript
Open issues
191
Contributors
36
First release
2025

Categories

LLMOps & AI ToolingAI & Machine LearningDeveloper Tools

Tags

AI AgentsLLMLLMOpsDeveloper FrameworkDeveloper ToolsRAG