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:[email protected]
      - type: TermsOfService
        url: https://github.com/4chan/4chan-API#api-terms-of-service
      - type: NaftikoCapability
        url: capabilities/4chan-api-boards.yaml
      - type: NaftikoCapability
        url: capabilities/4chan-api-threadlist.yaml
      - type: NaftikoCapability
        url: capabilities/4chan-api-catalog.yaml
      - type: NaftikoCapability
        url: capabilities/4chan-api-archive.yaml
      - type: NaftikoCapability
        url: capabilities/4chan-api-indexes.yaml
      - type: NaftikoCapability
        url: capabilities/4chan-api-threads.yaml
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:[email protected]
  - 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: [email protected]