Letta

Letta, formerly MemGPT, is a platform for building AI agents with persistent memory. Originating from UC Berkeley research, it implements an OS-inspired memory architecture where agents manage core memory (in-context, like RAM) and archival memory (external storage, like disk). This lets agents learn and self-improve across conversations rather than being stateless. Agent state is persisted in databases rather than Python variables. Available as open-source (Apache 2.0) for self-hosting, or as Letta Cloud with a free tier of 5,000 monthly credits.