Numbers API

openapi: 3.0.3
info:
  title: Numbers API
  version: '1.0.0'
  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, batches/ranges,
    JSONP callbacks, document.write embedding, sentence-fragment responses,
    and configurable not-found behavior.
  contact:
    name: Numbers API
    email: [email protected]
    url: http://numbersapi.com/
  license:
    name: Free for any use (community API)
    url: http://numbersapi.com/
servers:
  - url: http://numbersapi.com
    description: Numbers API production endpoint.
tags:
  - name: Trivia
    description: Trivia facts about integers.
  - name: Math
    description: Mathematical properties of integers.
  - name: Date
    description: Historical facts associated with a day of the year.
  - name: Year
    description: Historical facts associated with a year.
  - name: Batch
    description: Multiple facts returned in a single request as a JSON map.
paths:
  /{number}:
    get:
      operationId: getTrivia
      summary: Numbers API Get Trivia Fact
      description: >-
        Return a trivia fact about the supplied integer. This is the default
        endpoint when no `type` segment is given. Use the keyword `random`
        to receive a random trivia fact.
      tags:
        - Trivia
      parameters:
        - $ref: '#/components/parameters/NumberPath'
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Min'
        - $ref: '#/components/parameters/Max'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Trivia fact, returned as plain text by default or JSON when `json` is set.
          content:
            text/plain:
              schema:
                type: string
                example: 42 is the number of laws of cricket.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetTrivia200Example:
                  summary: Default getTrivia 200 response
                  x-microcks-default: true
                  value:
                    text: 42 is the number of laws of cricket.
                    found: true
                    number: 42
                    type: trivia
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{number}/trivia:
    get:
      operationId: getTriviaFact
      summary: Numbers API Get Trivia Fact Explicit
      description: >-
        Return a trivia fact about the supplied integer. Equivalent to
        `/{number}` but with an explicit `trivia` type segment.
      tags:
        - Trivia
      parameters:
        - $ref: '#/components/parameters/NumberPath'
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Min'
        - $ref: '#/components/parameters/Max'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Trivia fact, returned as plain text by default or JSON when `json` is set.
          content:
            text/plain:
              schema:
                type: string
                example: 23 is the number of times Julius Caesar was stabbed.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetTriviaFact200Example:
                  summary: Default getTriviaFact 200 response
                  x-microcks-default: true
                  value:
                    text: 23 is the number of times Julius Caesar was stabbed.
                    found: true
                    number: 23
                    type: trivia
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{number}/math:
    get:
      operationId: getMathFact
      summary: Numbers API Get Math Fact
      description: >-
        Return a mathematical fact about the supplied integer. Use the keyword
        `random` to receive a random math fact.
      tags:
        - Math
      parameters:
        - $ref: '#/components/parameters/NumberPath'
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Min'
        - $ref: '#/components/parameters/Max'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Math fact, returned as plain text by default or JSON when `json` is set.
          content:
            text/plain:
              schema:
                type: string
                example: 42 is the 5th Catalan number.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetMathFact200Example:
                  summary: Default getMathFact 200 response
                  x-microcks-default: true
                  value:
                    text: 42 is the 5th Catalan number.
                    found: true
                    number: 42
                    type: math
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /random/math:
    get:
      operationId: getRandomMathFact
      summary: Numbers API Get Random Math Fact
      description: >-
        Return a random mathematical fact. Equivalent to `/random/math`;
        an alias for `getMathFact` with `number=random`. Supports `min` and
        `max` to bound the random integer.
      tags:
        - Math
      parameters:
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Min'
        - $ref: '#/components/parameters/Max'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Random math fact.
          content:
            text/plain:
              schema:
                type: string
                example: 7 is the lowest dimension of a known exotic sphere.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetRandomMathFact200Example:
                  summary: Default getRandomMathFact 200 response
                  x-microcks-default: true
                  value:
                    text: 7 is the lowest dimension of a known exotic sphere.
                    found: true
                    number: 7
                    type: math
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /random/trivia:
    get:
      operationId: getRandomTriviaFact
      summary: Numbers API Get Random Trivia Fact
      description: >-
        Return a random trivia fact. Supports `min` and `max` to bound the
        random integer.
      tags:
        - Trivia
      parameters:
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Min'
        - $ref: '#/components/parameters/Max'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Random trivia fact.
          content:
            text/plain:
              schema:
                type: string
                example: 13 is the number of provinces and territories in Canada.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetRandomTriviaFact200Example:
                  summary: Default getRandomTriviaFact 200 response
                  x-microcks-default: true
                  value:
                    text: 13 is the number of provinces and territories in Canada.
                    found: true
                    number: 13
                    type: trivia
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /random/date:
    get:
      operationId: getRandomDateFact
      summary: Numbers API Get Random Date Fact
      description: >-
        Return a random date fact (a fact tied to a day of year, returned with
        the corresponding `month/day`).
      tags:
        - Date
      parameters:
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Random date fact.
          content:
            text/plain:
              schema:
                type: string
                example: April 1 is the day in 1976 that Apple Computer Company is founded by Steve Jobs, Steve Wozniak, and Ronald Wayne.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetRandomDateFact200Example:
                  summary: Default getRandomDateFact 200 response
                  x-microcks-default: true
                  value:
                    text: April 1 is the day in 1976 that Apple Computer Company is founded by Steve Jobs, Steve Wozniak, and Ronald Wayne.
                    found: true
                    number: 92
                    type: date
                    year: '1976'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /random/year:
    get:
      operationId: getRandomYearFact
      summary: Numbers API Get Random Year Fact
      description: >-
        Return a random year fact (a fact tied to a calendar year). The
        response includes the year as `number` and, when applicable, an
        associated `date` string.
      tags:
        - Year
      parameters:
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Random year fact.
          content:
            text/plain:
              schema:
                type: string
                example: 2012 is the year that the century's second and last solar transit of Venus occurs on June 6.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetRandomYearFact200Example:
                  summary: Default getRandomYearFact 200 response
                  x-microcks-default: true
                  value:
                    text: 2012 is the year that the century's second and last solar transit of Venus occurs on June 6.
                    found: true
                    number: 2012
                    type: year
                    date: June 6
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{month}/{day}/date:
    get:
      operationId: getDateFact
      summary: Numbers API Get Date Fact
      description: >-
        Return a historical fact about a specific day of the year, supplied as
        a `month/day` path (e.g. `2/29`, `04/1`). The keyword `random` may be
        used in place of `month/day` to get a random date fact, in which case
        the URL is `/random/date`.
      tags:
        - Date
      parameters:
        - name: month
          in: path
          required: true
          description: Month number, 1-12 (zero padding is accepted, e.g. `04`).
          schema:
            type: integer
            minimum: 1
            maximum: 12
          example: 2
        - name: day
          in: path
          required: true
          description: Day-of-month number, 1-31 (zero padding is accepted, e.g. `09`).
          schema:
            type: integer
            minimum: 1
            maximum: 31
          example: 29
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Date fact for the supplied month/day.
          content:
            text/plain:
              schema:
                type: string
                example: 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.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetDateFact200Example:
                  summary: Default getDateFact 200 response
                  x-microcks-default: true
                  value:
                    text: 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.
                    found: true
                    number: 60
                    type: date
                    year: '1504'
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{year}/year:
    get:
      operationId: getYearFact
      summary: Numbers API Get Year Fact
      description: >-
        Return a historical fact about a specific calendar year. Negative
        integers represent BC years. The keyword `random` may be used in place
        of `year` to get a random year fact, in which case the URL is
        `/random/year`.
      tags:
        - Year
      parameters:
        - name: year
          in: path
          required: true
          description: Year number; negative integers represent BC.
          schema:
            type: integer
          example: 1969
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
        - $ref: '#/components/parameters/Callback'
        - $ref: '#/components/parameters/Write'
      responses:
        '200':
          description: Year fact.
          content:
            text/plain:
              schema:
                type: string
                example: 1969 is the year that an estimated 500 million people worldwide watch Neil Armstrong take his historic first steps on the Moon.
            application/json:
              schema:
                $ref: '#/components/schemas/Fact'
              examples:
                GetYearFact200Example:
                  summary: Default getYearFact 200 response
                  x-microcks-default: true
                  value:
                    text: 1969 is the year that an estimated 500 million people worldwide watch Neil Armstrong take his historic first steps on the Moon.
                    found: true
                    number: 1969
                    type: year
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{numberRange}/batch:
    get:
      operationId: getBatchFacts
      summary: Numbers API Get Batch Facts
      description: >-
        Return facts for multiple numbers in a single response. The
        `numberRange` path segment is a comma-separated list of integers and
        `min..max` ranges (e.g. `1..3,10`). Responses are always a JSON map
        from number to fact, of at most 100 numbers. Although the underlying
        URL pattern is `/{numberRange}` (or `/{numberRange}/{type}`), this
        operation models the batch case explicitly for tooling clarity.
      tags:
        - Batch
      parameters:
        - name: numberRange
          in: path
          required: true
          description: Comma-separated list of integers and inclusive `min..max` ranges.
          schema:
            type: string
          example: 1..3,10
        - name: type
          in: query
          required: false
          description: Fact type to apply to all numbers in the batch.
          schema:
            type: string
            enum:
              - trivia
              - math
              - year
          example: trivia
        - $ref: '#/components/parameters/Json'
        - $ref: '#/components/parameters/Fragment'
        - $ref: '#/components/parameters/Notfound'
        - $ref: '#/components/parameters/Default'
      responses:
        '200':
          description: >-
            JSON map keyed by number. When `json` is set, each value is a
            `Fact` object; otherwise each value is the plain-text fact string.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BatchFacts'
              examples:
                GetBatchFacts200Example:
                  summary: Default getBatchFacts 200 response
                  x-microcks-default: true
                  value:
                    '1': 1 is the number of dimensions of a line.
                    '2': 2 is the number of polynucleotide strands in a DNA double helix.
                    '3': 3 is the number of sets needed to be won to win the whole match in volleyball.
                    '10': 10 is the highest score possible in Olympics gymnastics competitions.
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
components:
  parameters:
    NumberPath:
      name: number
      in: path
      required: true
      description: >-
        Integer to look up, or the keyword `random` to receive a random
        available fact.
      schema:
        type: string
        pattern: '^(random|-?\d+)$'
      example: '42'
    Json:
      name: json
      in: query
      required: false
      description: >-
        Return the fact as a JSON object (`{ text, found, number, type,
        date?, year? }`) instead of plain text. Equivalent to setting the
        request `Content-Type: application/json` header.
      schema:
        type: boolean
      example: true
    Fragment:
      name: fragment
      in: query
      required: false
      description: >-
        Return the fact as a sentence fragment (lowercase, no terminal
        punctuation) suitable for embedding in a larger sentence.
      schema:
        type: boolean
      example: true
    Notfound:
      name: notfound
      in: query
      required: false
      description: >-
        Behavior when no fact exists for the requested number. `default`
        returns a generic message (overridable with `default`), `floor` rounds
        down to the nearest number with a fact, and `ceil` rounds up.
      schema:
        type: string
        enum:
          - default
          - floor
          - ceil
        default: default
      example: floor
    Default:
      name: default
      in: query
      required: false
      description: Custom message to return when no fact exists for the requested number.
      schema:
        type: string
      example: Boring number is boring.
    Min:
      name: min
      in: query
      required: false
      description: >-
        Minimum value (inclusive) for random-number selection. Only meaningful
        when `number=random`.
      schema:
        type: integer
      example: 10
    Max:
      name: max
      in: query
      required: false
      description: >-
        Maximum value (inclusive) for random-number selection. Only meaningful
        when `number=random`.
      schema:
        type: integer
      example: 20
    Callback:
      name: callback
      in: query
      required: false
      description: >-
        JSONP callback function name. The response is wrapped as
        `<callback>("<fact>")`.
      schema:
        type: string
      example: showNumber
    Write:
      name: write
      in: query
      required: false
      description: >-
        Wrap the response in `document.write("<fact>")` so a single
        `<script src="...">` tag can render the fact inline. Equivalent to
        `callback=document.write`.
      schema:
        type: boolean
      example: true
  responses:
    NotFound:
      description: >-
        No fact was found for the requested number. The body still contains a
        plain-text or JSON message; the HTTP status reflects the lookup
        outcome only when `notfound` is left at its default.
      content:
        text/plain:
          schema:
            type: string
            example: 314159265358979 is a boring number.
        application/json:
          schema:
            $ref: '#/components/schemas/Fact'
          examples:
            NotFoundExample:
              summary: Default 404 response
              x-microcks-default: true
              value:
                text: 314159265358979 is a boring number.
                found: false
                number: 314159265358979
                type: trivia
  schemas:
    Fact:
      type: object
      description: A single Numbers API fact returned in JSON form.
      required:
        - text
        - number
        - found
        - type
      properties:
        text:
          type: string
          description: Plain-text fact about the number.
          example: 42 is the result given by Google and Bing for the query "the answer to life the universe and everything".
        number:
          type: number
          description: >-
            Floating-point number the fact pertains to. For date facts, this
            is the 1-indexed day of a leap year (e.g. 61 is March 1).
          example: 42
        found:
          type: boolean
          description: Whether a real fact was found for the requested number.
          example: true
        type:
          type: string
          description: Category of the returned fact.
          enum:
            - trivia
            - math
            - date
            - year
          example: trivia
        date:
          type: string
          description: Day of year associated with year facts, as a string (e.g. `June 6`).
          example: June 6
        year:
          type: string
          description: Year associated with date facts, as a string (e.g. `1969`).
          example: '1969'
    BatchFacts:
      type: object
      description: >-
        JSON map of number-keyed facts returned by a batch request. Each value
        is either a plain-text fact (default) or a `Fact` object (when `json`
        is set).
      additionalProperties:
        oneOf:
          - type: string
          - $ref: '#/components/schemas/Fact'
      example:
        '1': 1 is the number of dimensions of a line.
        '2': 2 is the number of polynucleotide strands in a DNA double helix.
        '3': 3 is the number of sets needed to be won to win the whole match in volleyball.
        '10': 10 is the highest score possible in Olympics gymnastics competitions.