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
      - type: NaftikoCapability
        url: capabilities/numbers-trivia.yaml
      - type: NaftikoCapability
        url: capabilities/numbers-math.yaml
      - type: NaftikoCapability
        url: capabilities/numbers-date.yaml
      - type: NaftikoCapability
        url: capabilities/numbers-year.yaml
      - type: NaftikoCapability
        url: capabilities/numbers-batch.yaml
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