Last updated 06-27-2026
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Letta
Letta is an AI research lab in San Francisco building machines that learn. Its flagship product, Letta Code, is a memory-first agent whose identity, skills, and capabilities evolve with experience rather than resetting each session. The lab envisions digital people that remember everything, learn continuously, and improve over time.
The work traces back to MemGPT, the UC Berkeley research on virtual context management that introduced the idea of treating LLM context like an operating system. Letta extends that foundation with sleep-time compute, git-tracked memory through MemFS, and continual learning in token space so agents carry knowledge across model generations.
Letta Code ships as a desktop app for macOS, Windows, and Linux, a CLI installed via npm, and a cloud layer called Constellation for managed state and remote access. Teams use it to build persistent coding agents, connect them to Slack or Discord, schedule proactive tasks, and run workloads across local or remote environments.
The company was founded by the MemGPT creators from UC Berkeley's Sky Computing Lab. It is backed by Jeff Dean, Clem Delangue, Cris Valenzuela, Jordan Tigani, Tristan Handy, Barry McCardel, Robert Nishihara, Sunflower Capital, Essence VC, and Felicis Ventures.
Agents keep memory, identity, and skills across sessions
Sleep-time compute lets agents learn during idle time
Git-tracked context through MemFS context repositories
Talk to agents over Slack, Discord, Telegram, or custom channels
Schedule proactive tasks or let agents set their own crons
Swap models without losing memory via BYOK or coding plans
Desktop app plus CLI: npm i -g @letta-ai/letta-code
Open source Letta Code runs locally with your own API keys at no cost.
Memory persists across sessions and model swaps through git-tracked MemFS.
Connects to Slack, Discord, Telegram, and custom channels where teams already work.
Backed by MemGPT research and a team from UC Berkeley's Sky Computing Lab.
Heavy coding workloads can exceed Pro quota quickly without external coding plans.
Constellation cloud features require signing in; fully local use skips managed state.
Enterprise and team seat pricing require contacting sales.
Is Letta Code free to use?
Yes. Letta Code is free with your own API keys from providers like OpenAI or Anthropic, or with external coding plans such as ChatGPT Codex and zAI. Constellation cloud features require a free account, which supports up to three agents with managed state.
What platforms does Letta Code run on?
Letta Code offers a desktop app for macOS (Apple Silicon and Intel), Windows, and Linux, plus a CLI installed with npm i -g @letta-ai/letta-code. The CLI requires Node.js 18 or newer.
What models does Letta Code support?
Letta Code works with your own API keys and coding plans, including OpenAI Codex and zAI. Constellation adds Letta Auto, which routes to frontier models balanced for intelligence, coding, and speed, with Auto Chat and Auto Fast variants.
What is Constellation in Letta?
Constellation is Letta's stateful agent cloud at chat.letta.com. It provides managed state, remote environments, and Letta Auto inference. Free accounts include up to three agents; paid plans raise agent limits and add Letta Auto quota.
How does Letta agent memory work?
Letta agents store context in git-tracked memory via MemFS context repositories. Skills, prompts, and experience persist across sessions and model swaps. Sleep-time compute lets agents process and rewrite memory during idle time instead of only at inference.
What does the Letta Pro plan include?
Letta Pro costs $20 per month for personal use. It includes Letta Auto weekly and monthly quota, pay-as-you-go overage, and up to 20 stateful agents. You can still bring your own API keys on all plans.