Mattermost website screenshot

Mattermost

Mattermost is an open-source collaboration platform for technical teams that combines secure team messaging, workflow automation, voice/video calling, and integrations as a self-hosted Slack alternative. The Mattermost REST API exposes full programmatic control over users, teams, channels, posts, files, integrations, plugins, and webhooks.

Mattermost publishes 5 APIs on the APIs.io network, including WebSocket API, Channels API, Posts API, and 2 more. Tagged areas include Messaging, Collaboration, Team Chat, Open Source, and DevOps.

The Mattermost catalog on APIs.io includes 1 event-driven AsyncAPI specification and 1 Spectral governance ruleset.

Mattermost’s developer surface includes authentication, documentation, signup flow, pricing, engineering blog, and 9 more developer resources.

🌐 Visit website 📡 Source on GitHub
38.3/100 thin ▬ flat Agent 44/100 agent ready Full breakdown ↓
scored 2026-07-28 · rubric v0.6
AccessSelf serve
6 APIs 1 MCP Servers
MessagingCollaborationTeam ChatOpen SourceDevOpsSelf-Hosted

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6
Composite quality — 38.3/100 · thin
Contract Quality 14.8 / 25
Developer Ergonomics 7.8 / 20
Commercial Clarity 3.7 / 20
Operational Transparency 0.7 / 13
Governance 5.0 / 12
Discoverability 7.4 / 10
Agent readiness — 44/100 · agent ready
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
MCP Server 12 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface 6 / 6
Agent Skills 0 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 0 / 4
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/mattermost: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 6

Individual APIs this provider publishes, each with its own machine-readable definition.

Mattermost REST API

REST API v4 for managing users, teams, channels, posts, threads, files, integrations, plugins, webhooks, slash commands, and OAuth applications. Authentication uses Personal Acc...

Mattermost WebSocket API

Real-time WebSocket event stream for Mattermost v4. Clients connect to /api/v4/websocket, authenticate via cookie, Authorization header, or an authentication_challenge action, a...

Mattermost Channels API

The Channels API from Mattermost — 7 operation(s) for channels.

Mattermost Posts API

The Posts API from Mattermost — 9 operation(s) for posts.

Mattermost Teams API

The Teams API from Mattermost — 6 operation(s) for teams.

Mattermost Users API

The Users API from Mattermost — 8 operation(s) for users.

Open Collections 1

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Mattermost REST API

OPEN COLLECTION

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

MCP Server

MCP SERVER

GraphQL 1

GraphQL schemas published by this provider.

Mattermost GraphQL Schema

Conceptual GraphQL schema for the [Mattermost](https://mattermost.com) open-source team messaging platform, derived from the [Mattermost REST API v4](https://api.mattermost.com/).

GRAPHQL

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Mattermost WebSocket API

Mattermost's WebSocket API delivers real-time events from a Mattermost server to authenticated clients and accepts a small set of WebSocket actions for client-to-server interact...

ASYNCAPI

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Mattermost API Rules

8 rules · 1 errors 7 warnings

SPECTRAL

Security Posture 4

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Mattermost Authentication

http · 1 scheme

SECURITY

Mattermost Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Mattermost Vulnerability Disclosure

security.txt · contact published

SECURITY

Mattermost Trust Center

SOC 2, ISO 27001, ISO 27017, ISO 27018, HIPAA, FedRAMP, GDPR

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Mattermost Agentic Access

43 operations · 29 acting

43 operations · 29 acting

AGENTIC

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 Signup
Signup

Documentation 1

Reference material describing how the API behaves

Documentation
Documentation

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess
AgenticAccess
 MCPServer
MCPServer

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization

Access & Security 4

Authentication, authorization, and security posture

TrustCenter
TrustCenter
 VulnerabilityDisclosure
VulnerabilityDisclosure
 DomainSecurity
DomainSecurity
 Authentication
Authentication

Commercial 1

Pricing, plans, and the legal terms of use

Pricing
Pricing

Company 3

The organization behind the API

LinkedIn
LinkedIn
 Website
Website
 Blog
Blog

Source (apis.yml)

apis.yml Raw ↑ 
aid: mattermost
name: Mattermost
description: Mattermost is an open-source collaboration platform for technical teams that combines secure team messaging,
  workflow automation, voice/video calling, and integrations as a self-hosted Slack alternative. The Mattermost REST API exposes
  full programmatic control over users, teams, channels, posts, files, integrations, plugins, and webhooks.
type: Index
accessModel:
  pricing: unknown
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/mattermost.png
tags:
- Messaging
- Collaboration
- Team Chat
- Open Source
- DevOps
- Self-Hosted
url: https://raw.githubusercontent.com/api-evangelist/mattermost/refs/heads/main/apis.yml
created: '2026-05-11'
modified: '2026-05-29'
specificationVersion: '0.19'
apis:
- aid: mattermost:rest-api
  name: Mattermost REST API
  description: REST API v4 for managing users, teams, channels, posts, threads, files, integrations, plugins, webhooks, slash
    commands, and OAuth applications. Authentication uses Personal Access Tokens or session tokens via Bearer authentication.
  humanURL: https://api.mattermost.com/
  baseURL: https://your-mattermost-server.com/api/v4
  tags:
  - Messaging
  - Users
  - Teams
  - Channels
  - Posts
  - Webhooks
  - Integrations
  properties:
  - type: Documentation
    url: https://api.mattermost.com/
  - type: APIReference
    url: https://developers.mattermost.com/integrate/reference/rest-api/
  - type: OpenAPI Source
    url: https://github.com/mattermost/mattermost-api-reference
  - type: Developer Guide
    url: https://developers.mattermost.com/contribute/more-info/server/rest-api/
  - url: graphql/mattermost-graphql.md
    type: GraphQL
- aid: mattermost:websocket-api
  name: Mattermost WebSocket API
  description: Real-time WebSocket event stream for Mattermost v4. Clients connect to /api/v4/websocket, authenticate via
    cookie, Authorization header, or an authentication_challenge action, and receive event envelopes (event, data, broadcast,
    seq) covering posts, channels, users, teams, reactions, typing, status, threads, plugins, and more. Client actions user_typing,
    get_statuses, and get_statuses_by_ids are supported over the same socket.
  humanURL: https://developers.mattermost.com/api-documentation
  baseURL: wss://your-mattermost-server.com/api/v4/websocket
  tags:
  - WebSocket
  - Events
  - Real-Time
  - Messaging
  - AsyncAPI
  properties:
  - type: Documentation
    url: https://developers.mattermost.com/api-documentation
  - type: AsyncAPI
    url: https://raw.githubusercontent.com/api-evangelist/mattermost/refs/heads/main/asyncapi/mattermost-asyncapi.yml
  - type: APIReference
    url: https://developers.mattermost.com/integrate/reference/rest-api/
- aid: mattermost:mattermost-channels-api
  name: Mattermost Channels API
  description: The Channels API from Mattermost — 7 operation(s) for channels.
  humanURL: https://api.mattermost.com/
  baseURL: https://your-mattermost-server.com/api/v4
  tags:
  - Channels
  properties:
  - type: OpenAPI
    url: openapi/mattermost-channels-api-openapi.yml
- aid: mattermost:mattermost-posts-api
  name: Mattermost Posts API
  description: The Posts API from Mattermost — 9 operation(s) for posts.
  humanURL: https://api.mattermost.com/
  baseURL: https://your-mattermost-server.com/api/v4
  tags:
  - Posts
  properties:
  - type: OpenAPI
    url: openapi/mattermost-posts-api-openapi.yml
- aid: mattermost:mattermost-teams-api
  name: Mattermost Teams API
  description: The Teams API from Mattermost — 6 operation(s) for teams.
  humanURL: https://api.mattermost.com/
  baseURL: https://your-mattermost-server.com/api/v4
  tags:
  - Teams
  properties:
  - type: OpenAPI
    url: openapi/mattermost-teams-api-openapi.yml
- aid: mattermost:mattermost-users-api
  name: Mattermost Users API
  description: The Users API from Mattermost — 8 operation(s) for users.
  humanURL: https://api.mattermost.com/
  baseURL: https://your-mattermost-server.com/api/v4
  tags:
  - Users
  properties:
  - type: OpenAPI
    url: openapi/mattermost-users-api-openapi.yml
common:
- type: AgenticAccess
  url: agentic-access/mattermost-agentic-access.yml
- type: TrustCenter
  url: security/mattermost-trust-center.yml
- type: VulnerabilityDisclosure
  url: security/mattermost-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/mattermost-domain-security.yml
- type: Authentication
  url: authentication/mattermost-authentication.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/mattermost
- type: Website
  url: https://mattermost.com
- type: Documentation
  url: https://docs.mattermost.com
- type: DeveloperPortal
  url: https://developers.mattermost.com/
- type: GitHubOrganization
  url: https://github.com/mattermost
- type: Signup
  url: https://mattermost.com/sign-up/
- type: Pricing
  url: https://mattermost.com/pricing/
- name: MCP Server
  url: https://github.com/mattermost/mmctl-mcp
  type: MCPServer
- url: https://mattermost.com/blog/feed/
  type: Blog
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com