Letta (formerly MemGPT) is an open-source agent framework and cloud platform specializing in long-term memory for AI agents. Its three-tier memory architecture (core memory in-context, recall memory as searchable history, archival memory as cold storage) lets agents remember facts and preferences indefinitely across sessions. The managed cloud adds an Agent Development Environment (ADE), hosted infrastructure, and scaling. In 2026 the company shipped Letta Code, a memory-first coding agent ranked #1 among model-agnostic open-source agents on Terminal-Bench (42.5%), and launched Channels as a replacement for LettaBot. Key features: - Three-tier memory architecture: core (in-context), recall (searchable history), archival (cold storage) - Model-agnostic: supports OpenAI, Anthropic, Mistral, and local models - Stateful agents that persist and self-update knowledge across sessions - Letta Code desktop app: memory-first coding agent (#1 model-agnostic open-source, Terminal-Bench 2026) - Channels: asynchronous messaging layer for agent interactions - Self-hosted open-source (Apache 2.0) or managed cloud
Free tier: up to 3 managed agents, BYOK. Pro: $20/month, up to 20 stateful agents plus Letta Auto model quota. Team/Enterprise: custom pricing.