Cat Facts (catfact.ninja) Facts API

openapi: 3.0.3
info:
  title: Cat Breeds Facts API
  description: 'A free, no-authentication REST API at catfact.ninja serving random cat trivia and a catalog of cat breeds. Three GET endpoints: /fact (a single random fact), /facts (paginated list of facts), and /breeds (paginated list of breeds). Designed as a canonical "hello world" public API for tutorials, demos, and agent tool examples.'
  contact:
    name: Cat Facts API
    email: contact@catfact.ninja
    url: https://catfact.ninja/
  license:
    name: Free Public API
    url: https://catfact.ninja/
  version: 1.0.0
  x-generated-from: documentation
  x-source-url: https://catfact.ninja/docs?api-docs.json
  x-last-validated: '2026-05-30'
servers:
- url: https://catfact.ninja
  description: Cat Facts API production server.
tags:
- name: Facts
  description: Random cat trivia, individually or in paginated lists.
paths:
  /fact:
    get:
      tags:
      - Facts
      summary: Get Random Fact
      description: Returns a single random cat fact. An optional max_length query parameter caps the returned fact length, which is useful for SMS, push notifications, and any other length-constrained surface.
      operationId: getRandomFact
      parameters:
      - name: max_length
        in: query
        description: Maximum length, in characters, of the returned fact.
        required: false
        schema:
          type: integer
          format: int32
          minimum: 1
          example: 140
      responses:
        '200':
          description: A random cat fact.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CatFact'
              examples:
                GetRandomFact200Example:
                  summary: Default getRandomFact 200 response
                  x-microcks-default: true
                  value:
                    fact: People who are allergic to cats are actually allergic to cat saliva or to cat dander.
                    length: 89
        '404':
          description: No fact matched the given constraints.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
              examples:
                GetRandomFact404Example:
                  summary: Default getRandomFact 404 response
                  value:
                    message: Fact not found
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /facts:
    get:
      tags:
      - Facts
      summary: Get a List of Facts
      description: Returns a paginated list of cat facts. Supports max_length (character cap per fact) and limit (page size) query parameters. The response follows Laravel's paginator format with current_page, per_page, total, last_page, links, and a data array of CatFact objects.
      operationId: getFacts
      parameters:
      - name: max_length
        in: query
        description: Maximum length, in characters, of each returned fact.
        required: false
        schema:
          type: integer
          format: int32
          minimum: 1
          example: 140
      - name: limit
        in: query
        description: Number of facts to return per page.
        required: false
        schema:
          type: integer
          format: int32
          minimum: 1
          example: 10
      responses:
        '200':
          description: A paginated list of cat facts.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CatFactList'
              examples:
                GetFacts200Example:
                  summary: Default getFacts 200 response
                  x-microcks-default: true
                  value:
                    current_page: 1
                    data:
                    - fact: Unlike dogs, cats do not have a sweet tooth.
                      length: 45
                    - fact: When a cat chases its prey, it keeps its head level.
                      length: 53
                    first_page_url: https://catfact.ninja/facts?page=1
                    from: 1
                    last_page: 111
                    last_page_url: https://catfact.ninja/facts?page=111
                    next_page_url: https://catfact.ninja/facts?page=2
                    path: https://catfact.ninja/facts
                    per_page: 2
                    prev_page_url: null
                    to: 2
                    total: 332
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
components:
  schemas:
    PaginationLink:
      type: object
      title: PaginationLink
      description: A single navigation link in a Laravel-style paginator response.
      properties:
        url:
          type: string
          nullable: true
          description: Target URL of the link, or null for disabled controls.
          example: https://catfact.ninja/facts?page=2
        label:
          type: string
          description: Display label (page number, "Previous", "Next", or "...").
          example: '2'
        active:
          type: boolean
          description: Whether this link represents the current page.
          example: false
    Error:
      type: object
      title: Error
      description: Generic error response payload.
      properties:
        message:
          type: string
          description: Human-readable error message.
          example: Fact not found
    CatFact:
      type: object
      title: CatFact
      description: A single cat trivia fact and its character length.
      properties:
        fact:
          type: string
          description: The cat fact text.
          example: Cats sleep 70% of their lives.
        length:
          type: integer
          format: int32
          description: Character length of the fact string.
          example: 30
      required:
      - fact
      - length
    CatFactList:
      type: object
      title: CatFactList
      description: Laravel-style paginated wrapper around a list of CatFact objects.
      properties:
        current_page:
          type: integer
          format: int32
          example: 1
        data:
          type: array
          items:
            $ref: '#/components/schemas/CatFact'
        first_page_url:
          type: string
          example: https://catfact.ninja/facts?page=1
        from:
          type: integer
          format: int32
          nullable: true
          example: 1
        last_page:
          type: integer
          format: int32
          example: 111
        last_page_url:
          type: string
          example: https://catfact.ninja/facts?page=111
        links:
          type: array
          items:
            $ref: '#/components/schemas/PaginationLink'
        next_page_url:
          type: string
          nullable: true
          example: https://catfact.ninja/facts?page=2
        path:
          type: string
          example: https://catfact.ninja/facts
        per_page:
          type: integer
          format: int32
          example: 10
        prev_page_url:
          type: string
          nullable: true
          example: null
        to:
          type: integer
          format: int32
          nullable: true
          example: 10
        total:
          type: integer
          format: int32
          example: 332