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
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
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:
- aid: 4chan:4chan-archive-api
  name: 4chan Archive API
  description: Per-board list of OP numbers for closed, archived threads.
  humanURL: https://github.com/4chan/4chan-API
  baseURL: https://a.4cdn.org
  tags:
  - Archive
  properties:
  - type: OpenAPI
    url: openapi/4chan-archive-api-openapi.yml
  - type: Documentation
    url: https://github.com/4chan/4chan-API
  - 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
- aid: 4chan:4chan-boards-api
  name: 4chan Boards API
  description: List of all boards on 4chan and 4channel and their per-board settings.
  humanURL: https://github.com/4chan/4chan-API
  baseURL: https://a.4cdn.org
  tags:
  - Boards
  properties:
  - type: OpenAPI
    url: openapi/4chan-boards-api-openapi.yml
  - type: Documentation
    url: https://github.com/4chan/4chan-API
  - 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
- aid: 4chan:4chan-catalog-api
  name: 4chan Catalog API
  description: >-
    Per-board catalog snapshot containing every OP and its preview replies, grouped by index page.
  humanURL: https://github.com/4chan/4chan-API
  baseURL: https://a.4cdn.org
  tags:
  - Catalog
  properties:
  - type: OpenAPI
    url: openapi/4chan-catalog-api-openapi.yml
  - type: Documentation
    url: https://github.com/4chan/4chan-API
  - 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
- aid: 4chan:4chan-indexes-api
  name: 4chan Indexes API
  description: >-
    Per-board, per-page index document of threads (each with a posts array including the OP and a small
    number of preview replies).
  humanURL: https://github.com/4chan/4chan-API
  baseURL: https://a.4cdn.org
  tags:
  - Indexes
  properties:
  - type: OpenAPI
    url: openapi/4chan-indexes-api-openapi.yml
  - type: Documentation
    url: https://github.com/4chan/4chan-API
  - 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
- aid: 4chan:4chan-threadlist-api
  name: 4chan Threadlist API
  description: >-
    Per-board summary list of every live thread (id, last-modified, reply count) grouped by index page.
  humanURL: https://github.com/4chan/4chan-API
  baseURL: https://a.4cdn.org
  tags:
  - Threadlist
  properties:
  - type: OpenAPI
    url: openapi/4chan-threadlist-api-openapi.yml
  - type: Documentation
    url: https://github.com/4chan/4chan-API
  - 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
- aid: 4chan:4chan-threads-api
  name: 4chan Threads API
  description: Single-thread document containing the OP and every reply.
  humanURL: https://github.com/4chan/4chan-API
  baseURL: https://a.4cdn.org
  tags:
  - Threads
  properties:
  - type: OpenAPI
    url: openapi/4chan-threads-api-openapi.yml
  - type: Documentation
    url: https://github.com/4chan/4chan-API
  - 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: AgenticAccess
    url: agentic-access/4chan-agentic-access.yml
  - type: VulnerabilityDisclosure
    url: security/4chan-vulnerability-disclosure.yml
  - type: DomainSecurity
    url: security/4chan-domain-security.yml
  - 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: SDKs
    title: Python Wrapper (BASC-py4chan, community)
    url: https://github.com/bibanon/BASC-py4chan
  - type: SDKs
    title: Python Wrapper (py-4chan, community)
    url: https://github.com/e000/py-4chan
  - type: SDKs
    title: Node.js Client (4chanjs, community)
    url: https://github.com/yocontra/4chanjs
  - type: SDKs
    title: Go Client (go-4chan-api, community)
    url: https://github.com/moshee/go-4chan-api
  - type: SDKs
    title: Rust Client (rchan, community)
    url: https://github.com/insomnimus/rchan
  - type: SDKs
    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