Letta is completely free with 3 features included. No paid tiers offered, making it perfect for budget-conscious users.
Letta is the production platform that evolved from the MemGPT research project. The core concept (LLM-managed virtual memory) is the same, but Letta adds a server architecture, REST API, ADE, multi-agent support, and production deployment features that weren't in the original MemGPT.
RAG retrieves relevant documents using vector similarity. Letta gives the agent active control over its memory — it decides what to store, search, update, and forget. RAG is passive retrieval; Letta is active memory management. They can be complementary, with archival memory functioning like a RAG-accessible store.
Yes. Letta supports OpenAI, Anthropic, local models via Ollama or vLLM, and other providers. However, self-directed memory management requires strong instruction-following capabilities, so smaller open-source models may not manage memory as effectively as GPT-4 or Claude.
It's being used in production by some teams, particularly for persistent assistant use cases. The server architecture is designed for production, but some features are still maturing. Evaluate carefully for your specific use case and plan for the operational complexity of running stateful agent servers.
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Last verified March 2026