Letta

aid: letta
url: https://raw.githubusercontent.com/api-evangelist/letta/refs/heads/main/apis.yml
name: Letta
x-type: company
description: >-
  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 agents, memory
  blocks, tools, sources (RAG), runs, and streaming responses. Open-source server is
  available on GitHub; Letta Cloud is the managed offering. Python and TypeScript SDKs
  ship alongside the REST API.
image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
tags:
  - AI
  - Agents
  - Memory
  - MemGPT
  - Stateful
  - Open Source
created: '2026-05-08'
modified: '2026-05-08'
specificationVersion: '0.19'
apis:
  - aid: letta:cloud
    name: Letta Cloud API
    description: >-
      REST API for managing stateful agents, memory blocks (in-context + archival/RAG),
      custom tools (sandbox, client-side, MCP), sources, runs, and streaming responses.
      Bearer token auth on Letta Cloud.
    image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
    humanURL: https://docs.letta.com/
    baseURL: https://api.letta.com
    tags:
      - Agents
      - Memory
      - Tools
      - Streaming
      - RAG
    properties:
      - type: Documentation
        url: https://docs.letta.com/
      - type: SignUp
        url: https://app.letta.com/
      - type: Pricing
        url: https://docs.letta.com/guides/api/plans
      - type: GitHub
        url: https://github.com/letta-ai/letta
      - type: LLMsTxt
        url: https://docs.letta.com/llms-full.txt
  - aid: letta:self-hosted
    name: Letta Self-Hosted Server
    description: >-
      Open-source Letta server for self-hosted agent deployments. Same REST API surface as
      Letta Cloud, free to run; pay only for hosting and underlying LLM API usage. Agents
      can be migrated between self-hosted and cloud via .af agent file format.
    image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
    humanURL: https://github.com/letta-ai/letta
    baseURL: https://localhost:8283
    tags:
      - Open Source
      - Self-Hosted
      - Agents
    properties:
      - type: GitHub
        url: https://github.com/letta-ai/letta
      - type: Documentation
        url: https://docs.letta.com/
common:
  - type: Website
    url: https://www.letta.com/
  - type: Documentation
    url: https://docs.letta.com/
  - type: GitHub
    url: https://github.com/letta-ai/letta
  - type: Plans
    url: plans/letta-plans-pricing.yml
  - type: RateLimits
    url: rate-limits/letta-rate-limits.yml
  - type: FinOps
    url: finops/letta-finops.yml
maintainers:
  - FN: Kin Lane
    email: [email protected]