Letta FAQs
Can’t find the answer to your question? Feel free to reach out to the Letta development team and community on Discord or GitHub!
Letta Platform
Who is Letta for?
Letta is for developers building stateful LLM applications that require advanced memory, such as:
- personalized chatbots that require long-term memory and personas that should be updated (self-edited) over time (e.g. companions)
- agents connected to external data sources, e.g. private enterprise deployments of ChatGPT-like applications (connected to your company’s data), or a medical assistant connected to a patient’s medical records
- agents connected to custom tools, e.g. a chatbot that can answer questions about the latest news by searching the web
- automated AI workflows, e.g. an agent that monitors your email inbox and sends you text alerts for urgent emails and a daily email summary
… and countless other use cases!
Can I use Letta locally?
Yes, Letta is an open source project and you can run it locally on your own machine.
When you run Letta locally, you have the option to connect the agents server to external API providers (e.g. OpenAI, Anthropic) or connect to local or self-hosted LLM providers (e.g. Ollama or vLLM).
Is Letta free to use?
The open source Letta software is free to use and permissively licensed under the Apache 2.0 license. Letta Cloud is a paid service and requires a Letta Cloud account to use.
What's the difference between open source Letta and Letta Cloud?
Letta Cloud is a fully managed service that allows you to create and deploy Letta agents without running any infrastructure. If you’d like to build production applications using the Letta API, consider using Letta Cloud.
Agent Development Environment (ADE)
How do I use the ADE locally?
To connect the ADE to your local Letta server, simply run your Letta server (make sure you can access localhost:8283) and go to https://app.letta.com.
If you would like to use the old version of the ADE (that runs on localhost), downgrade to Letta version <=0.5.0.
If I connect the ADE to my local server, does my agent data get uploaded to letta.com?
No, the data in your Letta server database stays on your machine. The Letta ADE web application simply connects to your local Letta server (via the REST API) and provides a graphical interface on top of it to visualize your local Letta data in your browser’s local state.
Do I have to use your ADE? Can I build my own?
The ADE is built on top of the (fully open source) Letta server and Letta Agents API. You can build your own application like the ADE on top of the REST API (view the documention here).
Self-hosted (local) Letta Server
Do I need to install Docker to use Letta?
No, you can install Letta using pip (via pip install -U letta), as well as from source (via poetry install).
What's the difference between installing with pip vs Docker?
Letta gives your agents persistence (they live indefinitely) by storing all your agent data in a database.
Letta is designed to be used with a PostgreSQL (the world’s most popular database), however, it is not possible to install PostgreSQL via pip, so the pip install of Letta defaults to using SQLite.
If you have a PostgreSQL instance running on your own computer, you can still connect Letta (installed via pip) to PostgreSQL by setting the environment variable LETTA_PG_URI.
Database migrations are not officially supported for Letta when using SQLite, so if you would like to ensure that you’re able to upgrade to the latest Letta version and migrate your Letta agents data, make sure that you’re using PostgreSQL as your Letta database backend. Full compatability table below: