Letta

Stateful agent runtime that manages its own OS-style tiered memory.

Letta (formerly MemGPT) is an open-source framework and platform for building stateful AI agents with long-term memory that persists across sessions. It manages an agent's memory hierarchy, including editable in-context memory and external recall storage, so agents can learn and self-improve over time, and it exposes agents through an API, CLI, and developer environment. It is notable for originating the MemGPT approach of treating LLM context like an operating-system memory hierarchy.