Letta (formerly MemGPT) is a stateful AI agents platform built around long-term memory, tool execution, and multi-agent coordination. The Letta REST API exposes 239 endpoints across 36 public resource categories — agents, memory blocks, archival memory, sources (RAG), custom tools (sandboxed/client-side/MCP), MCP servers, multi-agent groups, identities, runs, scheduled messages, and a streaming voice-mode endpoint. Open-source server (Apache-2.0, 22.9k+ stars) is available on GitHub; Letta Cloud is the managed offering; the Agent Development Environment (ADE) provides a web UI for inspecting context windows, memory blocks, and run history. Python and TypeScript SDKs ship alongside the REST API, and the open .af agent file format lets agents migrate between deployments.
APIs.json: https://raw.githubusercontent.com/api-evangelist/letta/refs/heads/main/apis.yml
- AI
- Agents
- Stateful Agents
- Memory
- MemGPT
- Continual Learning
- MCP
- Multi-Agent
- RAG
- Open Source
- Created: 2026-05-08
- Modified: 2026-05-22
REST API for managing stateful agents, memory blocks (in-context + archival/RAG), custom tools (sandboxed Python, client-side, MCP-delegated), sources, multi-agent groups (supervisor/round-robin/dynamic/sleep-time), MCP server registrations, runs, identities, scheduled messages, and a beta voice-mode streaming endpoint. 239 paths under /v1/. Bearer token auth (Authorization: Bearer $LETTA_API_KEY).
- Human URL: https://docs.letta.com/
- Base URL:
https://api.letta.com
- Agents
- Memory
- Tools
- Streaming
- RAG
- MCP
- Multi-Agent
- Documentation
- Sign Up
- Pricing
- Git Hub
- L L Ms Txt
- Changelog
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Open A P I Y A M L
- Spectral Ruleset
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
- JSON Schema — JSON Schema
Open-source Letta server (Apache-2.0) for self-hosted agent deployments. Same REST API surface as Letta Cloud, free to run; pay only for hosting and underlying LLM API usage. Default base URL is http://localhost:8283. Agents can be migrated between self-hosted and cloud via the open .af agent file format.
- Human URL: https://github.com/letta-ai/letta
- Base URL:
http://localhost:8283
- Open Source
- Self-Hosted
- Agents
- Docker
- Git Hub
- Documentation
- License
- Docker
- Agent File Format
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
Letta's memory-first coding agent — a CLI plus a desktop app (and an action for GitHub repos). "The memory-first coding agent that remembers and learns." Builds on the Letta Code SDK and the broader Letta platform; offered with personal plans (chat.letta.com) separate from the API Plan.
- Human URL: https://github.com/letta-ai/letta-code
- Base URL:
https://chat.letta.com
- Coding Agent
- CLI
- Desktop
- Git Hub
- SDK
- Git Hub Action
- Demo
- Skills
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Website
- Blog
- Documentation
- L L Ms Txt
- Git Hub
- Git Hub Org
- Python S D K
- Type Script S D K
- Sign In
- Pricing
- Plans
- Rate Limits
- Fin Ops
- Spectral Ruleset
- J S O N L D Context
- Vocabulary
- Agent File Format
- L L Ms Txt
FN: Kin Lane Email: kin@apievangelist.com