Numbers API

aid: numbers
name: Numbers API
description: >-
  Numbers API by David Hu and Mack Duan — a free, community-contributed HTTP API for interesting facts about numbers.
  Returns trivia, math, date, and year facts as plain text or JSON. Supports random numbers, ranges/batches, JSONP
  callbacks, document.write embedding, sentence-fragment responses, and configurable not-found behavior.
url: http://numbersapi.com/
specificationVersion: '0.20'
created: '2026-05-28'
modified: '2026-05-30'
x-source: public-apis/public-apis
x-category: Science & Math
x-tier: 3
x-tier-reason: opensource-community-api
tags:
  - Science And Math
  - Public APIs
  - Trivia
  - Numbers
  - Dates
  - Open Source
apis:
  - name: Numbers API
    description: >-
      HTTP API for trivia, math, date, and year facts about numbers. URL pattern is `/{number}/{type}` where type is one
      of `trivia`, `math`, `date`, or `year`. Numbers may be integers, the keyword `random`, a `month/day` date, or
      batch ranges. Responses default to plain text and can be returned as JSON via the `json` query parameter.
    humanURL: http://numbersapi.com/
    baseURL: http://numbersapi.com/
    tags:
      - Science And Math
      - Trivia
      - Numbers
    properties:
      - type: Documentation
        url: http://numbersapi.com/#api
      - type: APIReference
        url: http://numbersapi.com/#api
      - type: GettingStarted
        url: http://numbersapi.com/#api
      - type: OpenAPI
        url: openapi/numbers-openapi.yml
      - type: JSONSchema
        url: json-schema/numbers-fact-schema.json
      - type: JSONSchema
        url: json-schema/numbers-batch-facts-schema.json
      - type: JSONStructure
        url: json-structure/numbers-fact-structure.json
      - type: JSONStructure
        url: json-structure/numbers-batch-facts-structure.json
      - type: Example
        url: examples/numbers-fact-example.json
      - type: Example
        url: examples/numbers-trivia-fact-example.json
      - type: Example
        url: examples/numbers-math-fact-example.json
      - type: Example
        url: examples/numbers-date-fact-example.json
      - type: Example
        url: examples/numbers-year-fact-example.json
      - type: Example
        url: examples/numbers-batch-facts-example.json
common:
  - type: Website
    url: http://numbersapi.com/
  - type: Documentation
    url: http://numbersapi.com/#api
  - type: Blog
    url: http://david-hu.com/2012/03/05/announcing-numbers-api.html
  - type: Contact
    url: mailto:numbersapi@gmail.com
  - type: PublicAPIsListing
    url: https://github.com/public-apis/public-apis
  - type: SpectralRules
    url: rules/numbers-rules.yml
  - type: Vocabulary
    url: vocabulary/numbers-vocabulary.yml
  - type: JSONLD
    url: json-ld/numbers-context.jsonld
  - type: Features
    data:
      - name: Trivia Facts
        description: >-
          Return a piece of trivia about a number, e.g. `42 is the number of little squares forming the left side trail
          of Microsoft's Windows 98 logo`.
      - name: Math Facts
        description: Return a mathematical property of a number, e.g. `5 is the number of platonic solids`.
      - name: Date Facts
        description: >-
          Return a fact about a day of the year (month/day), e.g. `February 29 is the day in 1504 that Christopher
          Columbus uses his knowledge of a lunar eclipse to convince Native Americans to provide him with supplies`.
      - name: Year Facts
        description: >-
          Return a fact about a year, e.g. `1969 is the year that an estimated 500 million people worldwide watch Neil
          Armstrong take his historic first steps on the Moon`.
      - name: Random Numbers
        description: >-
          Use the keyword `random` in place of a number to get a random fact, optionally bounded by `min` and `max`
          query parameters.
      - name: JSON Responses
        description: >-
          Append `?json` (or send `Content-Type: application/json`) to receive the fact wrapped in an object with
          `text`, `found`, `number`, `type`, and optional `date`/`year` fields.
      - name: Sentence Fragment Mode
        description: >-
          Append `?fragment` to get the fact rephrased as a lowercase, no- terminal-punctuation fragment suitable for
          embedding in a larger sentence.
      - name: Configurable Not Found Behavior
        description: >-
          Use `notfound=default|floor|ceil` to control what happens when no fact exists for the requested number, with
          an optional custom `default=...` message.
      - name: JSONP Callback
        description: Pass `callback=functionName` to wrap the response in a JSONP function call.
      - name: Document.write Embed
        description: >-
          Pass `write` to wrap the response in `document.write(...)`, allowing a single `<script src="...">` to render
          the fact inline.
      - name: Batch Requests
        description: >-
          Request facts for multiple numbers in one call using comma-separated values and `min..max` ranges (up to 100
          numbers), returned as a JSON map.
      - name: CORS Support
        description: Supports cross-origin requests, allowing direct browser calls from any domain.
  - type: UseCases
    data:
      - name: Engagement Copy
        description: >-
          Insert living facts into marketing copy or dashboards, e.g. `We now have more users than the number of times
          Julius Caesar was stabbed`.
      - name: Calendar Widgets
        description: Pair `month/day/date` with a date picker or daily widget to surface a historical fact for the current day.
      - name: Anniversary and Year-in-Review
        description: Use `/{year}/year` to enrich anniversary, retrospective, and year-in-review content with curated facts.
      - name: Daily Random Trivia
        description: >-
          Power "fact of the day" features for chatbots, newsletters, screen savers, and home assistants using
          `/random/trivia`.
      - name: Math Education
        description: Surface mathematical properties of numbers in educational tools and worksheets via `/{n}/math`.
      - name: Mock and Demo Data
        description: >-
          Provide free, unauthenticated, low-latency text responses ideal for tutorials, demos, and beginner HTTP client
          exercises.
  - type: Integrations
    data:
      - name: jQuery
        description: The docs show a `$.get()` example loading a trivia fact directly into a DOM element.
      - name: Browser JavaScript
        description: Direct cross-origin requests via fetch/XHR are supported because the service emits permissive CORS headers.
      - name: JSONP Consumers
        description: The `callback` query parameter lets legacy JSONP clients consume facts as `functionName("...")` invocations.
      - name: HTML script tag
        description: >-
          The `write` query parameter wraps responses in `document.write()`, so a single `<script
          src="numbersapi.com/...">` tag can render a fact inline in static HTML.
      - name: Public APIs Directory
        description: Listed in public-apis/public-apis under the Science & Math category as a free, no-auth API.
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com