Stateful agent framework with long-term memory, evolved from the MemGPT research project.
Letta (formerly MemGPT) is a framework and platform for building stateful agents that maintain long-term memory across sessions. It implements memory management concepts from the MemGPT paper, giving agents self-editing memory, archival storage, and a persistent identity. Letta Cloud provides a hosted agent server and Agent Development Environment.
Open-source framework is free (Apache 2.0). Letta Cloud offers a free tier plus usage-based paid plans.