Library / SDK
Agents & OrchestrationRetrieval & Memory
Letta
1Stateful 2agents 3with 4long-term 5memory 6built-in.
the six Ws · specification
W1
Who
Open-source project, formerly known as MemGPT.
W2
What
Runs stateful agents with self-managed long-term memory.
W3
Where
A self-hosted server with a REST API.
W4
When
When agents must learn and remember over time.
W5
Why
Treats memory as a first-class, persistent resource.
W6
With
Any LLM provider and a database.