AI agents

Letta

An AI agent that remembers your past conversations and tasks.

Visit official page 日本語で詳しく見る

Popularity

★ 24k

Last update

August 2026

License / pricing

Apache-2.0

What it does

Letta helps you build AI agents that remember your interactions and learn from them over time. This means you can create a personalized AI that gets smarter and more helpful the more you use it, remembering past conversations and tasks.

Summary based on the project's own description. The Japanese page has a fuller beginner guide: setup difficulty, what to prepare, and a step-by-step start.

Screenshots & visuals

Before you start

Setup difficultySome setup needed
Command lineRequired
API keyRequired
Sends data onlineYes

Judged automatically from the project's own metadata. Always confirm on the official page.

Letta FAQ

Is Letta free?: Letta itself is free, but it needs an API key for an external AI service. That service charges separately, though some have a free tier.
Do I need to install anything or write code to use Letta?: It needs the command line. If you are not comfortable typing commands, expect to get stuck during setup.
Does Letta work on a phone?: No. It needs a computer.
Can I use Letta commercially?: The licence is Apache-2.0, which permits commercial use. Conditions such as keeping the copyright notice still apply, so read the licence text before shipping it inside something.

How it compares

The conditions that decide whether you can actually use it, side by side.

Tool	Command line	API key	Sends data out	Phone	Commercial use
Letta (this page)	Required	Required	Yes	No	Yes
cognee	Required	Required	Yes	No	Yes
memvid	Required	Not needed	No	No	Yes
MemOS	Required	Required	Yes	No	Yes

"Sends data out" means your input is uploaded to someone's server. Pick "No" when the material cannot leave your organisation.

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MemOS

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What it does

Summary based on the project's own description. The Japanese page has a fuller beginner guide: setup difficulty, what to prepare, and a step-by-step start.

Letta FAQ

Is Letta free?

Letta itself is free, but it needs an API key for an external AI service. That service charges separately, though some have a free tier.

Do I need to install anything or write code to use Letta?

It needs the command line. If you are not comfortable typing commands, expect to get stuck during setup.

Does Letta work on a phone?

No. It needs a computer.

Can I use Letta commercially?

The licence is Apache-2.0, which permits commercial use. Conditions such as keeping the copyright notice still apply, so read the licence text before shipping it inside something.

How it compares

The conditions that decide whether you can actually use it, side by side.

Tool	Command line	API key	Sends data out	Phone	Commercial use
Letta (this page)	Required	Required	Yes	No	Yes
cognee	Required	Required	Yes	No	Yes
memvid	Required	Not needed	No	No	Yes
MemOS	Required	Required	Yes	No	Yes

"Sends data out" means your input is uploaded to someone's server. Pick "No" when the material cannot leave your organisation.