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Letta is used to build stateful AI agents that remember information across sessions, manage long-running context, and interact with tools through an API. It is designed for developers building persistent assistants, coding agents, support agents, and agentic applications.
Letta is the platform that evolved from the MemGPT research project and agent design pattern. The company describes Letta as born from MemGPT at UC Berkeley and focused on production stateful agents.
Letta has a Free plan at $0/month with limited agents, limited Letta Auto usage, and support for bring-your-own API keys. Pro is $20/month and includes Letta Auto quota and up to 20 stateful agents. API usage starts at $20/month plus metered usage.
Traditional RAG usually retrieves relevant chunks from a vector store and inserts them into a prompt according to a retrieval rule. Letta adds an agent architecture where the agent can manage memory, choose when to retrieve, update stored context, and persist state across interactions.
Yes. Letta's documentation and pricing materials describe BYOK support, so users can bring their own API keys and route usage through provider accounts instead of relying only on bundled model usage.
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Last verified March 2026