openapi: 3.0.3
info:
  title: 4chan Read-Only JSON API
  description: >-
    Read-only JSON API for the 4chan and 4channel imageboards, originally launched in
    September 2012. All endpoints are served as static JSON documents from
    `a.4cdn.org` over `http://` or `https://`. The API exposes only the public,
    anonymous read surface of the site: board metadata, board catalogs, board
    threadlists, archive listings, board index pages, and individual thread documents.

    There is no authentication, no posting, and no per-user write surface. Only
    `GET`, `HEAD`, and `OPTIONS` are accepted. CORS is enabled only for origins
    `boards.4chan.org` and `boards.4channel.org`.

    Clients MUST send no more than one request per second, MUST set
    thread-polling intervals to at least 10 seconds (preferably higher), and SHOULD
    use `If-Modified-Since` so that unchanged threads return `304 Not Modified`.
  version: '2026-05-28'
  termsOfService: https://github.com/4chan/4chan-API#api-terms-of-service
  contact:
    name: 4chan API
    email: api@4chan.org
    url: https://github.com/4chan/4chan-API
  license:
    name: 4chan API Terms of Service
    url: https://github.com/4chan/4chan-API#api-terms-of-service
  x-generated-from: documentation
  x-source-url: https://github.com/4chan/4chan-API
  x-last-validated: '2026-05-28'
servers:
- url: https://a.4cdn.org
  description: Production 4chan read-only JSON API (HTTPS).
- url: http://a.4cdn.org
  description: Production 4chan read-only JSON API (HTTP, legacy clients only).
tags:
- name: Boards
  description: List of all boards on 4chan and 4channel and their per-board settings.
- name: Threadlist
  description: Per-board summary list of every live thread (id, last-modified, reply count) grouped by index page.
- name: Catalog
  description: Per-board catalog snapshot containing every OP and its preview replies, grouped by index page.
- name: Archive
  description: Per-board list of OP numbers for closed, archived threads.
- name: Indexes
  description: Per-board, per-page index document of threads (each with a posts array including the OP and a small number of preview replies).
- name: Threads
  description: Single-thread document containing the OP and every reply.
paths:
  /boards.json:
    get:
      operationId: getBoards
      summary: 4chan List All Boards
      description: >-
        Returns the comprehensive list of all 4chan and 4channel boards and their
        major settings (page count, per-page thread count, bump/image limits,
        cooldowns, feature flags, etc.). This is the canonical bootstrap call for
        any client — every other endpoint requires a board directory name from
        this document.
      tags:
      - Boards
      responses:
        '200':
          description: Successful response. Returns the full boards list.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BoardsResponse'
              examples:
                GetBoards200Example:
                  summary: Default getBoards 200 response
                  x-microcks-default: true
                  value:
                    boards:
                    - board: a
                      title: Anime & Manga
                      ws_board: 1
                      per_page: 15
                      pages: 10
                      max_filesize: 4194304
                      max_webm_filesize: 3145728
                      max_comment_chars: 2000
                      max_webm_duration: 120
                      bump_limit: 500
                      image_limit: 300
                      cooldowns:
                        threads: 600
                        replies: 60
                        images: 60
                      meta_description: "\"/a/ - Anime & Manga\" is 4chan's imageboard dedicated to the discussion of Japanese animation and manga."
                      spoilers: 1
                      custom_spoilers: 1
                      is_archived: 1
                    - board: po
                      title: Papercraft & Origami
                      ws_board: 1
                      per_page: 15
                      pages: 10
                      max_filesize: 4194304
                      max_webm_filesize: 3145728
                      max_comment_chars: 2000
                      max_webm_duration: 120
                      bump_limit: 500
                      image_limit: 300
                      cooldowns:
                        threads: 600
                        replies: 60
                        images: 60
                      meta_description: "\"/po/ - Papercraft & Origami\" is 4chan's imageboard for paper engineering."
                      is_archived: 1
        '304':
          description: Not Modified. Returned when an `If-Modified-Since` header matched.
        '404':
          description: Not Found.
        '503':
          description: Service Unavailable (rate limited or back-pressure).
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{board}/threads.json:
    get:
      operationId: getBoardThreadlist
      summary: 4chan Get Board Threadlist
      description: >-
        Returns a compact list of every live thread on the given board grouped by
        index page. Each thread entry contains only the OP number (`no`), the
        last-modified UNIX timestamp, and the reply count. Use this endpoint to
        detect new and updated threads cheaply; fetch the full thread or catalog
        only when `last_modified` changes.
      tags:
      - Threadlist
      parameters:
      - $ref: '#/components/parameters/BoardPath'
      responses:
        '200':
          description: Successful response. Returns the threadlist grouped by index page.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ThreadlistResponse'
              examples:
                GetBoardThreadlist200Example:
                  summary: Default getBoardThreadlist 200 response
                  x-microcks-default: true
                  value:
                  - page: 1
                    threads:
                    - no: 570368
                      last_modified: 1546294897
                      replies: 2
                    - no: 574933
                      last_modified: 1566530948
                      replies: 228
                  - page: 2
                    threads:
                    - no: 568362
                      last_modified: 1566367619
                      replies: 55
        '304':
          description: Not Modified.
        '404':
          description: Board not found.
        '503':
          description: Service Unavailable.
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{board}/catalog.json:
    get:
      operationId: getBoardCatalog
      summary: 4chan Get Board Catalog
      description: >-
        Returns the full catalog snapshot for the given board: every OP with its
        attributes and a short list of preview replies, grouped by index page. This
        is the largest per-board document and mirrors the public catalog page at
        `boards.4channel.org/{board}/catalog`.
      tags:
      - Catalog
      parameters:
      - $ref: '#/components/parameters/BoardPath'
      responses:
        '200':
          description: Successful response. Returns the catalog as an array of pages.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CatalogResponse'
              examples:
                GetBoardCatalog200Example:
                  summary: Default getBoardCatalog 200 response
                  x-microcks-default: true
                  value:
                  - page: 1
                    threads:
                    - no: 570368
                      sticky: 1
                      closed: 1
                      now: 12/31/18(Mon)17:05:48
                      name: Anonymous
                      sub: Welcome to /po/!
                      com: Welcome to /po/! We specialize in origami, papercraft, and everything that's relevant to paper engineering.
                      filename: yotsuba_folding
                      ext: .png
                      w: 530
                      h: 449
                      tn_w: 250
                      tn_h: 211
                      tim: 1546293948883
                      time: 1546293948
                      md5: uZUeZeB14FVR+Mc2ScHvVA==
                      fsize: 516657
                      resto: 0
                      capcode: mod
                      semantic_url: welcome-to-po
                      replies: 2
                      images: 2
                      omitted_posts: 0
                      omitted_images: 0
                      last_replies:
                      - no: 570371
                        now: 12/31/18(Mon)17:21:29
                        name: Anonymous
                        com: FAQ reply.
                        time: 1546294889
                        resto: 570368
                      last_modified: 1546294897
        '304':
          description: Not Modified.
        '404':
          description: Board not found.
        '503':
          description: Service Unavailable.
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{board}/archive.json:
    get:
      operationId: getBoardArchive
      summary: 4chan Get Board Archive
      description: >-
        Returns the list of archived (closed, read-only) thread OP numbers for the
        given board. Archived threads remain viewable until 4chan automatically
        deletes them. Not every board has archives enabled — boards without an
        archive return 404.
      tags:
      - Archive
      parameters:
      - $ref: '#/components/parameters/BoardPath'
      responses:
        '200':
          description: Successful response. Returns an array of archived OP numbers.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ArchiveResponse'
              examples:
                GetBoardArchive200Example:
                  summary: Default getBoardArchive 200 response
                  x-microcks-default: true
                  value:
                  - 571958
                  - 572866
                  - 574195
                  - 574342
                  - 574378
                  - 574398
                  - 574417
                  - 574426
                  - 574435
                  - 574453
                  - 574486
                  - 574510
                  - 574586
                  - 574588
        '304':
          description: Not Modified.
        '404':
          description: Board not found or archive not enabled for this board.
        '503':
          description: Service Unavailable.
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{board}/{page}.json:
    get:
      operationId: getBoardIndexPage
      summary: 4chan Get Board Index Page
      description: >-
        Returns a single index page for the given board. Each index page contains
        an array of threads, and each thread contains its OP plus a small number
        of preview replies. The maximum page number for a board comes from the
        `pages` field on the matching entry in `/boards.json`.
      tags:
      - Indexes
      parameters:
      - $ref: '#/components/parameters/BoardPath'
      - $ref: '#/components/parameters/PagePath'
      responses:
        '200':
          description: Successful response. Returns the page's threads.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/IndexPageResponse'
              examples:
                GetBoardIndexPage200Example:
                  summary: Default getBoardIndexPage 200 response
                  x-microcks-default: true
                  value:
                    threads:
                    - posts:
                      - no: 570368
                        sticky: 1
                        closed: 1
                        now: 12/31/18(Mon)17:05:48
                        name: Anonymous
                        sub: Welcome to /po/!
                        com: Welcome to /po/!
                        filename: yotsuba_folding
                        ext: .png
                        w: 530
                        h: 449
                        tn_w: 250
                        tn_h: 211
                        tim: 1546293948883
                        time: 1546293948
                        md5: uZUeZeB14FVR+Mc2ScHvVA==
                        fsize: 516657
                        resto: 0
                        capcode: mod
                        semantic_url: welcome-to-po
                        replies: 2
                        images: 2
                        unique_ips: 1
        '304':
          description: Not Modified.
        '404':
          description: Board not found or page out of range.
        '503':
          description: Service Unavailable.
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{board}/thread/{thread}.json:
    get:
      operationId: getThread
      summary: 4chan Get Thread
      description: >-
        Returns the full document for a single thread on the given board: the OP
        post object followed by every reply. To poll a thread for new replies,
        send `If-Modified-Since` on subsequent requests and treat `304` as "no
        change"; the minimum polling interval per the 4chan API rules is 10
        seconds, with longer intervals preferred.
      tags:
      - Threads
      parameters:
      - $ref: '#/components/parameters/BoardPath'
      - $ref: '#/components/parameters/ThreadPath'
      responses:
        '200':
          description: Successful response. Returns the thread's posts array.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ThreadResponse'
              examples:
                GetThread200Example:
                  summary: Default getThread 200 response
                  x-microcks-default: true
                  value:
                    posts:
                    - no: 570368
                      sticky: 1
                      closed: 1
                      now: 12/31/18(Mon)17:05:48
                      name: Anonymous
                      sub: Welcome to /po/!
                      com: Welcome to /po/! We specialize in origami and papercraft.
                      filename: yotsuba_folding
                      ext: .png
                      w: 530
                      h: 449
                      tn_w: 250
                      tn_h: 211
                      tim: 1546293948883
                      time: 1546293948
                      md5: uZUeZeB14FVR+Mc2ScHvVA==
                      fsize: 516657
                      resto: 0
                      capcode: mod
                      semantic_url: welcome-to-po
                      replies: 2
                      images: 2
                      unique_ips: 1
                    - no: 570370
                      now: 12/31/18(Mon)17:14:56
                      name: Anonymous
                      com: FAQs about papercraft.
                      filename: papercraft faq
                      ext: .png
                      w: 318
                      h: 704
                      tn_w: 56
                      tn_h: 125
                      tim: 1546294496751
                      time: 1546294496
                      md5: 0EqXBb4gGIyzQiaApMdFAA==
                      fsize: 285358
                      resto: 570368
                      capcode: mod
        '304':
          description: Not Modified.
        '404':
          description: Board not found or thread does not exist.
        '503':
          description: Service Unavailable.
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
components:
  parameters:
    BoardPath:
      name: board
      in: path
      required: true
      description: >-
        Board directory short name (e.g. `a`, `b`, `g`, `pol`, `po`, `v`). The
        full list of valid values is the `board` field on each entry in
        `/boards.json`.
      schema:
        type: string
        pattern: '^[a-z0-9]+$'
        minLength: 1
        maxLength: 8
        example: po
      example: po
    PagePath:
      name: page
      in: path
      required: true
      description: >-
        Index page number, starting at `1`. The maximum value is the `pages`
        field on the matching entry in `/boards.json` (commonly 10 or 15).
      schema:
        type: integer
        minimum: 1
        maximum: 20
        example: 3
      example: 3
    ThreadPath:
      name: thread
      in: path
      required: true
      description: The OP number of the thread to retrieve.
      schema:
        type: integer
        minimum: 1
        example: 570368
      example: 570368
  schemas:
    Cooldowns:
      type: object
      description: Per-board cooldown intervals (in seconds) between successive posts of each type.
      properties:
        threads:
          type: integer
          description: Minimum seconds between consecutive thread creations from the same poster.
          example: 600
        replies:
          type: integer
          description: Minimum seconds between consecutive replies from the same poster.
          example: 60
        images:
          type: integer
          description: Minimum seconds between consecutive image posts from the same poster.
          example: 60
    Board:
      type: object
      description: A single board on 4chan or 4channel and its configured settings.
      required:
      - board
      - title
      - ws_board
      - per_page
      - pages
      - max_filesize
      - max_webm_filesize
      - max_comment_chars
      - max_webm_duration
      - bump_limit
      - image_limit
      - cooldowns
      - meta_description
      properties:
        board:
          type: string
          description: Board directory short name (used as the path segment for all per-board endpoints).
          example: a
        title:
          type: string
          description: Human-readable board title displayed at the top of the board.
          example: Anime & Manga
        ws_board:
          type: integer
          description: '`1` if the board is worksafe, `0` otherwise.'
          enum: [0, 1]
          example: 1
        per_page:
          type: integer
          description: Number of threads displayed on a single index page.
          example: 15
        pages:
          type: integer
          description: Total number of index pages on the board.
          example: 10
        max_filesize:
          type: integer
          description: Maximum file size allowed for non-`.webm` attachments, in bytes.
          example: 4194304
        max_webm_filesize:
          type: integer
          description: Maximum file size allowed for `.webm` attachments, in bytes.
          example: 3145728
        max_comment_chars:
          type: integer
          description: Maximum number of characters allowed in a single post comment.
          example: 2000
        max_webm_duration:
          type: integer
          description: Maximum allowed duration of a `.webm` attachment, in seconds.
          example: 120
        bump_limit:
          type: integer
          description: Maximum number of replies before a thread stops bumping to the top.
          example: 500
        image_limit:
          type: integer
          description: Maximum number of image replies before further image replies are discarded.
          example: 300
        cooldowns:
          $ref: '#/components/schemas/Cooldowns'
        meta_description:
          type: string
          description: SEO `<meta>` description content for the board's catalog page.
          example: '"/a/ - Anime & Manga" is 4chan''s imageboard dedicated to the discussion of Japanese animation and manga.'
        spoilers:
          type: integer
          description: '`1` if spoilered images are enabled on this board.'
          enum: [0, 1]
          example: 1
        custom_spoilers:
          type: integer
          description: Number of custom spoiler image variants the board provides.
          example: 1
        is_archived:
          type: integer
          description: '`1` if the board has its archive enabled.'
          enum: [0, 1]
          example: 1
        board_flags:
          type: object
          description: Map of board-specific flag codes to human-readable flag names.
          additionalProperties:
            type: string
          example:
            AB: Flag Name AB
            XY: Flag Name XY
        country_flags:
          type: integer
          description: '`1` if poster country flags are enabled on this board.'
          enum: [0, 1]
          example: 0
        user_ids:
          type: integer
          description: '`1` if per-thread poster ID tags are enabled.'
          enum: [0, 1]
          example: 0
        oekaki:
          type: integer
          description: '`1` if users can submit drawings via the in-browser Oekaki app.'
          enum: [0, 1]
          example: 0
        sjis_tags:
          type: integer
          description: '`1` if the `[sjis]` Shift-JIS drawing tag is supported.'
          enum: [0, 1]
          example: 0
        code_tags:
          type: integer
          description: '`1` if `[code]` syntax-highlighted blocks are supported.'
          enum: [0, 1]
          example: 0
        math_tags:
          type: integer
          description: '`1` if `[math]` / `[eqn]` TeX rendering is supported.'
          enum: [0, 1]
          example: 0
        text_only:
          type: integer
          description: '`1` if image posting is disabled on the board.'
          enum: [0, 1]
          example: 0
        forced_anon:
          type: integer
          description: '`1` if the name field is disabled on the board.'
          enum: [0, 1]
          example: 0
        webm_audio:
          type: integer
          description: '`1` if `.webm` files with audio tracks are allowed.'
          enum: [0, 1]
          example: 0
        require_subject:
          type: integer
          description: '`1` if OPs are required to include a subject.'
          enum: [0, 1]
          example: 0
        min_image_width:
          type: integer
          description: Minimum allowed width of uploaded images, in pixels.
          example: 100
        min_image_height:
          type: integer
          description: Minimum allowed height of uploaded images, in pixels.
          example: 100
    BoardsResponse:
      type: object
      description: Top-level response from `/boards.json`.
      required:
      - boards
      properties:
        boards:
          type: array
          description: Every board on 4chan and 4channel.
          items:
            $ref: '#/components/schemas/Board'
    Post:
      type: object
      description: >-
        A single post — either an OP (when `resto == 0`) or a reply (when `resto`
        is the OP id). Many fields appear only on OPs (`replies`, `images`,
        `sticky`, `closed`, `archived`, …) or only on posts with an attached
        file.
      required:
      - 'no'
      - resto
      - now
      - time
      - name
      properties:
        'no':
          type: integer
          description: Numeric post ID.
          example: 570368
        resto:
          type: integer
          description: For replies, the OP ID this post replies to. For OPs, `0`.
          example: 0
        sticky:
          type: integer
          description: '`1` if the thread is pinned to the top of the board (OP only).'
          enum: [0, 1]
          example: 1
        closed:
          type: integer
          description: '`1` if the thread is closed to new replies (OP only).'
          enum: [0, 1]
          example: 1
        now:
          type: string
          description: Localized post timestamp in `MM/DD/YY(Day)HH:MM` (or `HH:MM:SS`) format, EST/EDT.
          example: 12/31/18(Mon)17:05:48
        time:
          type: integer
          description: UNIX timestamp the post was created.
          example: 1546293948
        name:
          type: string
          description: Display name used for the post (defaults to `Anonymous`).
          example: Anonymous
        trip:
          type: string
          description: 'User tripcode in the form `!tripcode` or `!!securetripcode`.'
          example: '!K.WeEabc'
        id:
          type: string
          description: Poster ID (8 chars) — present only when the board has per-thread poster IDs enabled.
          example: ABcd1234
        capcode:
          type: string
          description: Staff capcode on the post.
          enum:
          - mod
          - admin
          - admin_highlight
          - manager
          - developer
          - founder
          example: mod
        country:
          type: string
          description: ISO 3166-1 alpha-2 country code of the poster, or `XX` if unknown.
          example: US
        country_name:
          type: string
          description: Human-readable country name of the poster.
          example: United States
        board_flag:
          type: string
          description: Board-specific flag code (only on boards with board flags enabled).
          example: AB
        flag_name:
          type: string
          description: Board-specific flag display name.
          example: Flag Name AB
        sub:
          type: string
          description: OP subject (OP only, when set).
          example: Welcome to /po/!
        com:
          type: string
          description: Post comment as HTML-escaped string.
          example: 'Welcome to /po/! We specialize in origami, papercraft, and everything that''s relevant to paper engineering.'
        tim:
          type: integer
          description: UNIX timestamp + microtime that the attachment was uploaded — also the file ID for `i.4cdn.org`.
          example: 1546293948883
        filename:
          type: string
          description: Original filename of the attachment as uploaded.
          example: yotsuba_folding
        ext:
          type: string
          description: Attachment file extension.
          enum:
          - .jpg
          - .png
          - .gif
          - .pdf
          - .swf
          - .webm
          example: .png
        fsize:
          type: integer
          description: Attachment file size, in bytes.
          example: 516657
        md5:
          type: string
          description: 24-character packed base64 MD5 hash of the attachment.
          example: uZUeZeB14FVR+Mc2ScHvVA==
        w:
          type: integer
          description: Attachment width in pixels.
          example: 530
        h:
          type: integer
          description: Attachment height in pixels.
          example: 449
        tn_w:
          type: integer
          description: Thumbnail width in pixels.
          example: 250
        tn_h:
          type: integer
          description: Thumbnail height in pixels.
          example: 211
        filedeleted:
          type: integer
          description: '`1` if the post had a file and that file has been deleted.'
          enum: [0, 1]
          example: 0
        spoiler:
          type: integer
          description: '`1` if the attachment is spoilered.'
          enum: [0, 1]
          example: 0
        custom_spoiler:
          type: integer
          description: Custom spoiler ID `1-10` (only on boards with custom spoilers).
          minimum: 1
          maximum: 10
          example: 1
        replies:
          type: integer
          description: Total number of replies in the thread (OP only).
          example: 2
        images:
          type: integer
          description: Total number of image replies in the thread (OP only).
          example: 2
        bumplimit:
          type: integer
          description: '`1` once the thread has reached its bump limit (OP only).'
          enum: [0, 1]
          example: 0
        imagelimit:
          type: integer
          description: '`1` once the thread has reached its image-reply limit (OP only).'
          enum: [0, 1]
          example: 0
        tag:
          type: string
          description: Category of `.swf` upload on `/f/` (OP only, `/f/` only).
          example: Game
        semantic_url:
          type: string
          description: SEO-friendly URL slug for the thread (OP only).
          example: welcome-to-po
        since4pass:
          type: integer
          description: Year the poster bought a 4chan Pass (only when the poster opted in).
          example: 2018
        unique_ips:
          type: integer
          description: Number of unique posters in the thread (OP only, only when the thread is live).
          example: 1
        m_img:
          type: integer
          description: '`1` if a mobile-optimized variant of the attachment exists.'
          enum: [0, 1]
          example: 1
        archived:
          type: integer
          description: '`1` once the thread has been archived (OP only).'
          enum: [0, 1]
          example: 1
        archived_on:
          type: integer
          description: UNIX timestamp the thread was archived (OP only).
          example: 1566530948
        omitted_posts:
          type: integer
          description: Replies omitted from a catalog/index preview (OP only on catalog/index responses).
          example: 1
        omitted_images:
          type: integer
          description: Image replies omitted from a catalog/index preview (OP only on catalog/index responses).
          example: 1
        last_modified:
          type: integer
          description: UNIX timestamp the thread was last modified (OP only on catalog/threadlist responses).
          example: 1566530948
        last_replies:
          type: array
          description: Most recent reply objects shown in a catalog preview (OP only on catalog responses).
          items:
            $ref: '#/components/schemas/Post'
    ThreadResponse:
      type: object
      description: Top-level response from `/{board}/thread/{thread}.json`.
      required:
      - posts
      properties:
        posts:
          type: array
          description: The OP followed by every reply in the thread, in chronological order.
          items:
            $ref: '#/components/schemas/Post'
    IndexPageThread:
      type: object
      description: Wrapper around the posts visible for one thread inside an index-page response.
      required:
      - posts
      properties:
        posts:
          type: array
          description: OP plus preview replies for this thread.
          items:
            $ref: '#/components/schemas/Post'
    IndexPageResponse:
      type: object
      description: Top-level response from `/{board}/{page}.json`.
      required:
      - threads
      properties:
        threads:
          type: array
          description: Every thread visible on the requested index page.
          items:
            $ref: '#/components/schemas/IndexPageThread'
    ThreadlistEntry:
      type: object
      description: Compact thread summary used in the per-board threadlist.
      required:
      - 'no'
      - last_modified
      - replies
      properties:
        'no':
          type: integer
          description: Thread OP ID.
          example: 570368
        last_modified:
          type: integer
          description: UNIX timestamp the thread was last modified.
          example: 1546294897
        replies:
          type: integer
          description: Number of replies in the thread.
          example: 2
    ThreadlistPage:
      type: object
      description: One index page in a threadlist response.
      required:
      - page
      - threads
      properties:
        page:
          type: integer
          description: Index page number this entry belongs to.
          example: 1
        threads:
          type: array
          description: Compact thread entries on this page.
          items:
            $ref: '#/components/schemas/ThreadlistEntry'
    ThreadlistResponse:
      type: array
      description: Top-level response from `/{board}/threads.json` — an array of pages, each with its threadlist.
      items:
        $ref: '#/components/schemas/ThreadlistPage'
    CatalogPage:
      type: object
      description: One index page in a catalog response.
      required:
      - page
      - threads
      properties:
        page:
          type: integer
          description: Index page number this catalog page entry belongs to.
          example: 1
        threads:
          type: array
          description: Catalog thread entries (each is an OP `Post` object enriched with `last_replies`).
          items:
            $ref: '#/components/schemas/Post'
    CatalogResponse:
      type: array
      description: Top-level response from `/{board}/catalog.json` — an array of pages, each containing OP threads with preview replies.
      items:
        $ref: '#/components/schemas/CatalogPage'
    ArchiveResponse:
      type: array
      description: Top-level response from `/{board}/archive.json` — an array of archived OP numbers.
      items:
        type: integer
        description: An archived OP ID.
        example: 571958