Letta

aid: letta
url: https://raw.githubusercontent.com/api-evangelist/letta/refs/heads/main/apis.yml
name: Letta
kind: 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 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.
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
tags:
  - AI
  - Agents
  - Stateful Agents
  - Memory
  - MemGPT
  - Continual Learning
  - MCP
  - Multi-Agent
  - RAG
  - Open Source
created: '2026-05-08'
modified: '2026-05-22'
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 (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`).
    image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
    humanURL: https://docs.letta.com/
    baseURL: https://api.letta.com
    tags:
      - Agents
      - Memory
      - Tools
      - Streaming
      - RAG
      - MCP
      - Multi-Agent
    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
      - type: Changelog
        url: https://www.letta.com/blog
      - type: OpenAPI
        url: openapi/letta-openapi.json
      - type: OpenAPIYAML
        url: openapi/letta-openapi.yml
      - type: SpectralRuleset
        url: rules/letta-rules.yml
      - type: JSONSchema
        url: json-schema/letta-agent-schema.json
      - type: JSONSchema
        url: json-schema/letta-block-schema.json
      - type: JSONSchema
        url: json-schema/letta-tool-schema.json
      - type: JSONSchema
        url: json-schema/letta-source-schema.json
      - type: JSONSchema
        url: json-schema/letta-run-schema.json
      - type: JSONSchema
        url: json-schema/letta-group-schema.json
      - type: JSONSchema
        url: json-schema/letta-identity-schema.json
      - type: JSONSchema
        url: json-schema/letta-message-schema.json
      - type: JSONSchema
        url: json-schema/letta-passage-schema.json
      - type: JSONSchema
        url: json-schema/letta-archive-schema.json
      - type: JSONSchema
        url: json-schema/letta-job-schema.json
      - type: JSONSchema
        url: json-schema/letta-llm-config-schema.json
      - type: JSONSchema
        url: json-schema/letta-embedding-config-schema.json
      - type: JSONSchema
        url: json-schema/letta-provider-schema.json
  - aid: letta:self-hosted
    name: Letta Self-Hosted Server
    description: >-
      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.
    image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
    humanURL: https://github.com/letta-ai/letta
    baseURL: http://localhost:8283
    tags:
      - Open Source
      - Self-Hosted
      - Agents
      - Docker
    properties:
      - type: GitHub
        url: https://github.com/letta-ai/letta
      - type: Documentation
        url: https://docs.letta.com/
      - type: License
        url: https://github.com/letta-ai/letta/blob/main/LICENSE
      - type: Docker
        url: https://github.com/letta-ai/letta/blob/main/Dockerfile
      - type: AgentFileFormat
        url: https://github.com/letta-ai/agent-file
      - type: OpenAPI
        url: openapi/letta-openapi.json
  - aid: letta:letta-code
    name: Letta Code
    description: >-
      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.
    image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
    humanURL: https://github.com/letta-ai/letta-code
    baseURL: https://chat.letta.com
    tags:
      - Coding Agent
      - CLI
      - Desktop
    properties:
      - type: GitHub
        url: https://github.com/letta-ai/letta-code
      - type: SDK
        url: https://github.com/letta-ai/letta-code-sdk
      - type: GitHubAction
        url: https://github.com/letta-ai/letta-code-action
      - type: Demo
        url: https://github.com/letta-ai/letta-oss-ui
      - type: Skills
        url: https://github.com/letta-ai/skills
common:
  - type: LinkedIn
    url: https://www.linkedin.com/company/letta-ai
  - type: Website
    url: https://www.letta.com/
  - type: Blog
    url: https://www.letta.com/blog
  - type: Documentation
    url: https://docs.letta.com/
  - type: LLMsTxt
    url: https://docs.letta.com/llms-full.txt
  - type: GitHub
    url: https://github.com/letta-ai
  - type: GitHubOrg
    url: https://github.com/letta-ai
  - type: PythonSDK
    url: https://github.com/letta-ai/letta-python
  - type: TypeScriptSDK
    url: https://github.com/letta-ai/letta-node
  - type: SignIn
    url: https://app.letta.com/
  - type: Pricing
    url: https://docs.letta.com/guides/api/plans
  - type: Plans
    url: plans/letta-plans-pricing.yml
  - type: RateLimits
    url: rate-limits/letta-rate-limits.yml
  - type: FinOps
    url: finops/letta-finops.yml
  - type: SpectralRuleset
    url: rules/letta-rules.yml
  - type: JSONLDContext
    url: json-ld/letta-context.jsonld
  - type: Vocabulary
    url: vocabulary/letta-vocabulary.yml
  - type: AgentFileFormat
    url: https://github.com/letta-ai/agent-file
  - type: LLMsTxt
    url: https://docs.letta.com/llms.txt
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com