Letta Agent File (.af)
Letta Agent File (.af) is an open standard file format for serializing stateful AI agents.
Who it is for: Users who export their .af files via ADE or API, users who deploy Agent Files to their own Letta servers via ADE, REST API, or SDK, and creators who contribute exported agent files to public repositories
Core capabilities
- Agent State Encapsulation: Packages system prompts, editable memory, tool configurations, and LLM settings into an Agent File.
- Cross-Server Mobility and Deployment: Agent Files can be used to move agents between cloud and on-premises agent servers and deployed to users' own Letta servers via ADE, REST API, or SDK.
- Export and Version Control: Users can export their own .af files via ADE or API and perform checkpointing and version control of agent states.
- Export Key Clearing: When exporting agents with tool execution keys, Agent File sets these keys to null.
- Document Organization and Retrieval: Letta Filesystem provides an interface for organizing and referencing PDFs, transcribed text, and other documents, along with three built-in tools: grep, open, and semantic_search.
Pricing
Unknown
Updated 2026-08-24