Letta review

Q: How do I install Letta?

Run npm install -g @letta-ai/letta-code. The install section above has the other options from the project's README.

Letta is a platform for building stateful AI agents with memory that can learn and improve over time.

Updated Nov 1, 2026. Review written Oct 22, 2026 from the project's own sources; usage data refreshed every Monday.

TL;DR

Letta, formerly MemGPT, is a platform for building stateful agents whose memory persists and improves with use. Letta is for developers who want coding agents, personal assistants, AI coworkers in chat apps, or stateful agents embedded in TypeScript applications. Letta's agent harness is open source and runs in a terminal UI, a self-hosted App Server, the web, or Letta Cloud.

25.3kGitHub stars
+77new stars, week of Oct 25
~116kdownloads a week, −16% vs 4-week avg
#36in RAG, data and memory this week

Letta at a glance

Category: RAG, data and memory
Maintained by: Letta (organization, @letta-ai on GitHub)
License: Apache 2.0
Repository: github.com/letta-ai/letta
Website: docs.letta.com
npm package: @letta-ai/letta-client 1.12.1
PyPI package: letta 0.34.12
Latest release: letta 0.34.12 on PyPI, Oct 12, 2026
First published: Oct 11, 2023

What Letta does

Letta builds stateful agents with memory that persists and can learn and improve over time.
Letta provides an interactive terminal UI, launched with the letta command, for working with agents locally.
Letta runs an App Server for local or self-hosted agents.
Letta connects agents to Slack, Telegram, Discord, and custom channels.
Letta offers an Agent SDK for building agents into TypeScript applications.
Letta supports Skills for reusable workflows, Schedules for recurring prompts, and Mods for extending the harness.
Letta Cloud keeps agent memory, identity, and conversations available across computers.

How to install and start using Letta

With npm

npm install -g @letta-ai/letta-code

Requirements

npm, to install the @letta-ai/letta-code package.
An LLM provider configured for your agents.
Python 3.9 or later for the letta PyPI package.

First steps

Install Letta globally from npm with the @letta-ai/letta-code package.
Run letta to launch the interactive terminal UI.
Choose an LLM provider, then follow the quickstart to chat with the Tutor agent.
Run letta server to host agents locally or on your own infrastructure.

Who Letta is for

Developers embedding stateful agents with persistent memory into TypeScript applications.
Developers who want a memory-first coding agent in the terminal.
Teams running AI coworkers in Slack, Telegram, or Discord.
Users automating recurring work with schedules and reusable skills.

Limitations to know

Letta's current source lives in letta-ai/letta-code; the letta-ai/letta repo's V1 API server is retired and kept on an archive branch.
Letta channels for local-backend agents require keeping the channel server running on infrastructure you manage.
Letta Server 0.16.7 removed block limit enforcement as a breaking change.

Is Letta growing? Usage data

In the week of Oct 25–31, 2026, Letta ranked #362 on the Devtoolwatch Board and #36 in RAG, data and memory, with a momentum score of 17 out of 100. Its main package had about 116k downloads that week, −16% against its own 4-week average.

New GitHub stars per week for the last 12 weeks, from GitHub's stargazer history (today's stargazers by the week they starred).

Show the weekly numbers

New GitHub stars per week for Letta
Week of	New stars
Aug 9, 2026	115
Aug 16, 2026	97
Aug 23, 2026	144
Aug 30, 2026	142
Sep 6, 2026	95
Sep 13, 2026	91
Sep 20, 2026	99
Sep 27, 2026	133
Oct 4, 2026	95
Oct 11, 2026	95
Oct 18, 2026	89
Oct 25, 2026	77

On Hacker News

Letta: Letta is a framework for creating LLM services with memory, 121 points and 22 comments (Mar 7, 2025)
Letta Code: a memory-first coding agent, 6 points and 3 comments (Dec 16, 2025)

The Board ranks tools by four signals each week: new stars, new stars for the repo's size, added downloads and download growth beyond the market. How the ranking works.

Letta alternatives

Other RAG, data and memory tools on the Board in the week of Oct 25–31, 2026, by momentum:

RAG, data and memory ranked by momentum, the week of Oct 25–31, 2026
Rank	Tool	Stars	Downloads/wk
#1	XERJXERJ is a local-first search engine and MCP server for AI agents, packaged as one Rust binary with an Elasticsearch-compatible API.	17.9k	–
#2	MemvidMemvid is a single-file memory layer for AI agents that packages data, embeddings, search indexes, and metadata into one portable .mv2 file.	17.3k	–
#3	LEANNLEANN is a Python vector database and RAG library that recomputes embeddings on demand to keep indexes small on personal devices.	13.7k	–
#4	GraphifyGraphify is an AI coding assistant skill that turns a codebase, with its docs, PDFs, images and videos, into a queryable knowledge graph.	140k	480.7k
#5	MarkItDownMarkItDown is a lightweight Python utility from Microsoft that converts PDFs, Office documents, images, audio and other files to…	193.2k	4.7M
#6	FirecrawlFirecrawl is an API and open source project to search, scrape, crawl, and interact with web pages, returning LLM-ready markdown or JSON…	197.4k	2.9M

All RAG, data and memory tools, ranked

Recent Letta releases

0.16.8, May 14, 2026
0.16.7, Mar 31, 2026
0.16.6, Mar 4, 2026
0.16.5, Feb 24, 2026
0.16.4, Jan 29, 2026

Letta FAQ

Is Letta free and open source?

Yes. Letta's source code is on GitHub (letta-ai/letta) under the Apache 2.0 license, so you can use it for free. Its website also links to a pricing page (https://docs.letta.com/pricing) for any paid plans.

How do I install Letta?

Run npm install -g @letta-ai/letta-code. The install section above has the other options from the project's README.

Is Letta still maintained?

Yes. The letta-ai/letta repository was last updated on Oct 18, 2026, and the latest release, letta 0.34.12 on PyPI, came out on Oct 12, 2026.

How popular is Letta?

Letta has 25.3k GitHub stars as of Nov 1, 2026. It gained 77 new stars in the week of Oct 25–31, 2026, against a 12-week average of 106 a week. Its main package had about 116k downloads that week, −16% against its own 4-week average. That made it #36 among RAG, data and memory tools on the Devtoolwatch Board.

Letta vs Mem0: how do they compare?

Letta and Mem0 are both tracked by Devtoolwatch as RAG, data and memory tools. Letta has 25.3k GitHub stars and Mem0 has 68.2k. In the week of Oct 25–31, 2026, Letta's main package had 116k downloads and Mem0's had 884.1k. Mem0 is a memory layer for AI agents and apps that stores and retrieves user, session, and agent context across interactions. Mem0 review.

Letta vs LangGraph: how do they compare?

Letta and LangGraph are both tracked by Devtoolwatch. Letta has 25.3k GitHub stars and LangGraph has 44.2k. In the week of Oct 25–31, 2026, Letta's main package had 116k downloads and LangGraph's had 18.5M. LangGraph is a low-level orchestration framework and runtime for building, managing, and deploying long-running, stateful agents in Python or JavaScript. LangGraph review.

What are the best alternatives to Letta?

Other RAG, data and memory tools on the Devtoolwatch Board in the week of Oct 25–31, 2026, by momentum: XERJ (#1), Memvid (#2), LEANN (#3), Graphify (#4), MarkItDown (#5). The alternatives table above has their numbers.

Is Letta the same as MemGPT?

Yes. Letta was formerly known as MemGPT. The project is actively developed, and its current source code lives in the letta-ai/letta-code repository.

Can I self-host Letta?

Yes. Letta's App Server runs local or self-hosted agents with the letta server command. Letta Cloud is the managed alternative for keeping memory and conversations available across computers.

Is Letta open source?

Yes. The Letta agent harness is fully open source, according to the Letta documentation.

What can I build with Letta?

Letta builds coding agents, personal assistants, AI coworkers in chat apps, and stateful agents embedded in your own applications.

What happened to the Letta V1 API server?

The Letta V1 API server is retired. It remains on the archive branch with existing tags and releases for reproducibility, but active projects should use letta-code.

Sources

Letta README badge

Maintainers can show the tool's weekly Board rank in their README:

[![Devtoolwatch](https://index.devtoolwatch.com/badge/letta.svg)](https://index.devtoolwatch.com/tools/letta/)

How this page is made: Devtoolwatch writes each review from the project's README, releases, package metadata and website, with an AI model, then checks every claim against the source it cites and drops what the sources don't support. The numbers come from Devtoolwatch's daily GitHub snapshots, GitHub's stargazer history, and the npm and PyPI download APIs. Spotted an error? Email [email protected].