aid: cat-facts-catfact
name: Cat Facts (catfact.ninja)
description: >-
  Cat Facts is a free, no-authentication community REST API at catfact.ninja that serves random
  cat trivia and a catalog of cat breeds. It exposes three documented endpoints — a single random
  fact, a paginated list of facts, and a paginated list of breeds — and ships a Swagger UI based
  OpenAPI 3.0 document at /docs. The service is widely used in API onboarding tutorials, demos,
  and sample apps because it requires no API key and returns small, predictable JSON payloads.
url: https://catfact.ninja/
image: https://catfact.ninja/docs/asset/favicon-32x32.png
specificationVersion: '0.20'
created: '2026-05-28'
modified: '2026-05-30'
x-source: public-apis/public-apis
x-type: opensource
x-category: Animals
x-tier: 3
x-tier-reason: bulk-registered-from-public-apis
tags:
  - Animals
  - Cats
  - Trivia
  - Public APIs
  - Community
  - No Authentication
  - REST
apis:
  - name: Cat Facts API
    description: >-
      REST API exposing 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) — return Laravel-style paginated JSON for the list endpoints.
    humanURL: https://catfact.ninja/
    baseURL: https://catfact.ninja
    image: https://catfact.ninja/docs/asset/favicon-32x32.png
    tags:
      - Animals
      - Cats
      - Trivia
      - Public APIs
    properties:
      - type: Documentation
        url: https://catfact.ninja/
      - type: SwaggerUI
        url: https://catfact.ninja/
      - type: OpenAPI
        url: openapi/cat-facts-catfact-openapi.yml
      - type: OpenAPISource
        url: https://catfact.ninja/docs?api-docs.json
      - type: NaftikoCapability
        url: capabilities/cat-facts-catfact-facts.yaml
      - type: NaftikoCapability
        url: capabilities/cat-facts-catfact-breeds.yaml
common:
  - type: Website
    url: https://catfact.ninja/
  - type: SwaggerUI
    url: https://catfact.ninja/
  - type: OpenAPI
    url: https://catfact.ninja/docs?api-docs.json
  - type: ContactEmail
    url: mailto:contact@catfact.ninja
  - type: PublicAPIsListing
    url: https://github.com/public-apis/public-apis
  - type: Authentication
    title: No Authentication Required
    url: https://catfact.ninja/
  - type: Tools
    title: MCP Server (Community — cursethevulgar)
    url: https://github.com/cursethevulgar/catfact-mcp-server
  - type: Tools
    title: MCP Server (Community — mtrmarko)
    url: https://github.com/mtrmarko/cat-facts-mcp
  - type: Tools
    title: MCP Server (Community — Volspan)
    url: https://github.com/volspan-deployments/cat-facts-mcp
  - type: SpectralRules
    url: rules/cat-facts-catfact-rules.yml
  - type: Vocabulary
    url: vocabulary/cat-facts-catfact-vocabulary.yml
  - type: JSONLDContext
    url: json-ld/cat-facts-catfact-context.jsonld
features:
  - name: Free and Open
    description: >-
      No API key, no signup, no quota header. Anyone can hit catfact.ninja and start getting JSON
      back. Ideal for first-class onboarding examples in tutorials and SDK quickstarts.
  - name: Paginated Listings
    description: >-
      The /facts and /breeds endpoints return Laravel-style paginated responses with current_page,
      last_page, per_page, total, and a links array suitable for "next/prev" UI patterns.
  - name: Length-Filtered Facts
    description: >-
      Both /fact and /facts accept a max_length query parameter, letting clients restrict trivia
      length for SMS-friendly, push-notification-friendly, or banner use cases.
  - name: Self-Describing OpenAPI
    description: >-
      A live OpenAPI 3.0 document is published at /docs?api-docs.json and rendered as Swagger UI
      at /docs — usable directly by codegen tools, Postman import, and AI agent toolkits.
useCases:
  - name: API Onboarding Tutorials
    description: >-
      Used in countless "hello-world" REST tutorials because it returns small JSON, requires no
      auth, and is CORS-friendly. A canonical first call for browsers, mobile apps, and SDKs.
  - name: SMS and Chatbot Daily Facts
    description: >-
      The original Cat Facts service became a meme around texting friends a daily cat fact.
      catfact.ninja is the easiest backend for any "daily fact" bot, including SMS, Discord, and
      Slack integrations.
  - name: Load Testing and Demo Apps
    description: >-
      Engineering teams point load generators, screen-recording demos, and observability sample
      apps at catfact.ninja because it tolerates traffic, returns tiny payloads, and never
      requires credential rotation.
  - name: MCP and Agent Tool Demos
    description: >-
      Several community Model Context Protocol servers wrap catfact.ninja as a "hello world" tool
      because the surface is small, safe, and read-only — perfect for showing Claude using a tool.
integrations:
  - name: Public APIs Index
    description: >-
      Listed in the popular public-apis/public-apis index as a free, no-auth Animals API.
  - name: Community MCP Servers
    description: >-
      At least three community-built MCP servers wrap the catfact.ninja endpoints as Claude tools.
  - name: Swagger UI
    description: >-
      Ships a live Swagger UI at https://catfact.ninja/ that imports the OpenAPI spec from /docs.
solutions:
  - name: Lowest-Friction Demo API
    description: >-
      When you need a public, free, no-auth REST API to demo SDK generation, OpenAPI tooling,
      mock servers, or agent tool calls, catfact.ninja is the smallest acceptable surface area.
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com