4chan

aid: 4chan
name: 4chan
description: >-
  4chan is a simple image-based bulletin board where anyone can post comments and share images across topic-specific
  boards. 4chan exposes a read-only JSON API (launched September 2012) that serves the same board, thread, catalog, and
  archive data consumed by the public site via static JSON files at a.4cdn.org. The API supports GET/HEAD/OPTIONS only —
  there is no posting, authentication, or write surface.
url: https://github.com/4chan/4chan-API
image: https://s.4cdn.org/image/fp/logo-transparent.png
specificationVersion: '0.20'
created: '2026-05-28'
modified: '2026-05-28'
x-source: public-apis/public-apis
x-type: company
x-category: Social
x-tier: 2
x-tier-reason: documented-read-only-json-api-with-active-community-clients
tags:
  - Social
  - Bulletin Board
  - Imageboard
  - Read Only
  - JSON
  - Public APIs
  - Community
apis:
  - name: 4chan Read-Only JSON API
    description: >-
      Read-only HTTP JSON API serving boards.json, threads.json, catalog.json, archive.json, board index pages, and
      individual thread documents from a.4cdn.org. Mirrors the data visible at boards.4chan.org / boards.4channel.org.
      No authentication, no write operations. CORS allowed only from boards.4chan.org and boards.4channel.org origins.
    humanURL: https://github.com/4chan/4chan-API
    baseURL: https://a.4cdn.org
    image: https://s.4cdn.org/image/fp/logo-transparent.png
    tags:
      - Social
      - Imageboard
      - Read Only
    properties:
      - type: Documentation
        url: https://github.com/4chan/4chan-API
      - type: OpenAPI
        url: openapi/4chan-api.yml
      - type: SignUp
        url: https://github.com/4chan/4chan-API#api-rules
      - type: Support
        url: mailto:api@4chan.org
      - type: TermsOfService
        url: https://github.com/4chan/4chan-API#api-terms-of-service
common:
  - type: Website
    url: https://www.4chan.org
  - type: Documentation
    url: https://github.com/4chan/4chan-API
  - type: GitHubOrganization
    url: https://github.com/4chan
  - type: SourceCode
    url: https://github.com/4chan/4chan-JS
    title: 4chan native browser extension source
  - type: ContactEmail
    url: mailto:api@4chan.org
  - type: Tools
    title: MCP Server (community, unofficial)
    url: https://github.com/sh0n0/chan-mcp-server
  - type: SDK
    title: Python Wrapper (BASC-py4chan, community)
    url: https://github.com/bibanon/BASC-py4chan
  - type: SDK
    title: Python Wrapper (py-4chan, community)
    url: https://github.com/e000/py-4chan
  - type: SDK
    title: Node.js Client (4chanjs, community)
    url: https://github.com/yocontra/4chanjs
  - type: SDK
    title: Go Client (go-4chan-api, community)
    url: https://github.com/moshee/go-4chan-api
  - type: SDK
    title: Rust Client (rchan, community)
    url: https://github.com/insomnimus/rchan
  - type: SDK
    title: Racket Client (yotsubAPI, community)
    url: https://github.com/g-gundam/yotsubAPI
  - type: Tools
    title: BA Thread Archiver (community)
    url: https://github.com/hydrusnetwork/BA-4chan-thread-archiver
  - type: PublicAPIsListing
    url: https://github.com/public-apis/public-apis
  - type: Plans
    url: plans/4chan-plans-pricing.yml
  - type: RateLimits
    url: rate-limits/4chan-rate-limits.yml
  - type: Vocabulary
    url: vocabulary/4chan-vocabulary.yml
  - type: SpectralRules
    url: rules/4chan-rules.yml
  - type: JSONLD
    url: json-ld/4chan-context.jsonld
features:
  - name: Read-Only JSON Catalog
    description: >-
      Static JSON representations of boards, threads, catalogs, and archives are served from a.4cdn.org; clients use
      standard HTTP semantics including If-Modified-Since for caching.
  - name: No Authentication
    description: >-
      The API requires no API key, no token, and no account; it is fully anonymous and serves the same data visible to
      anonymous web visitors.
  - name: HTTP Caching Built In
    description: >-
      The API requires clients to send If-Modified-Since headers on repeated requests, allowing 304 Not Modified
      responses and reducing server load.
  - name: CORS Restricted to 4chan Origins
    description: >-
      CORS is enabled but only for origins boards.4chan.org and boards.4channel.org via HTTP or HTTPS; only
      GET/OPTIONS/HEAD methods are accepted.
  - name: Per-Board Catalog
    description: >-
      Every board (a, b, g, pol, po, etc.) exposes catalog, threadlist, archive, and per-page index endpoints with the
      same shape, making bulk crawling trivial.
  - name: Static Media Domains
    description: >-
      User-uploaded images and thumbnails live at i.4cdn.org/{board}/{tim}.{ext}; static site assets including flags,
      spoiler images, and capcode icons live at s.4cdn.org.
useCases:
  - name: Read-Only Board Crawlers
    description: >-
      Build research crawlers that periodically snapshot board catalogs, threads, and archives while respecting the 1
      request per second limit and 10 second per-thread refresh floor.
  - name: Thread Archivers
    description: >-
      Mirror archived threads and their attached media to durable storage for academic study or cultural preservation
      (see BA Thread Archiver, Ayase / Asagi).
  - name: Imageboard Analytics
    description: >-
      Use threads.json and catalog.json to chart posting volume, reply velocity, and moderator/admin capcode activity
      across boards over time.
  - name: Language Models and Markov Chains
    description: >-
      Feed cleaned post comments from catalog.json and thread.json into text generation experiments (see
      4chanMarkovText).
  - name: Static Site Mirrors
    description: >-
      Combine boards.json + per-board catalog/thread JSON to build static site mirrors of individual threads suitable
      for read-only display.
integrations:
  - name: BASC-py4chan
    description: Python wrapper providing Pythonic access to boards, threads, and posts.
  - name: 4chanjs
    description: Node.js and browser client for the 4chan JSON API.
  - name: go-4chan-api
    description: Go client for crawling and consuming 4chan board JSON.
  - name: rchan
    description: Rust crate exposing typed boards/threads/posts and a basic client.
  - name: Ayase / Asagi
    description: Archive middleware that ingests 4chan JSON and stores posts in SQL for replay.
  - name: chan-mcp-server (community)
    description: Unofficial Model Context Protocol server exposing 4chan boards/threads/catalog as MCP tools.
solutions:
  - name: Imageboard Research Archive
    description: >-
      Combine threads.json polling with archive.json snapshots and i.4cdn.org media downloads to build a long-term
      archive that respects the published rate limits.
  - name: Capcode Activity Dashboard
    description: Use catalog.json/thread.json capcode and id fields to surface moderator and admin activity per board over time.
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com