Letta

Letta is a platform for building stateful AI agents whose memory, identity, and capabilities persist and develop through use. Teams can create personalized agents with custom skills, tools, and harness modifications, then communicate with them through Slack, Discord, Telegram, or custom channels. Agents can schedule work, review past runs, and connect to a device, sandbox, or virtual machine as a remote environment. MemFS tracks context such as skills and prompts with Git, while sleep-time compute supports learning outside an active conversation. Letta also supports multiple model routes and lets users bring API keys or compatible subscription plans. It covers both personal agents and API-based team applications. Costs depend on the plan, model tokens, active agents, tool-execution time, and overage usage, so workloads with heavy tool calls or long coding sessions need careful budget monitoring.