openapi: 3.1.2
info:
  title: Frankfurter Currencies historical-rates API
  description: Frankfurter is an open-source API for current and historical foreign exchange rates, sourcing currency data from public providers like the European Central Bank.
  version: 1.0.0
  license:
    name: MIT
    url: https://github.com/lineofflight/frankfurter/blob/main/LICENSE
  contact:
    url: https://github.com/lineofflight/frankfurter/issues
  x-generated-from: upstream
  x-last-validated: '2026-05-29'
servers:
- url: https://api.frankfurter.dev/v1
tags:
- name: historical-rates
  description: Historical exchange rates for specific dates and periods
paths:
  /{date}:
    get:
      tags:
      - historical-rates
      summary: Frankfurter Get Rates for a Past Date
      description: Returns historical rates for the working day closest to the specified date
      parameters:
      - name: date
        in: path
        description: The date for the historical rates
        required: true
        schema:
          $ref: '#/components/schemas/date'
      - $ref: '#/components/parameters/base'
      - $ref: '#/components/parameters/symbols'
      responses:
        '200':
          description: Historical rates
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ratesOnDate'
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{start_date}..:
    get:
      tags:
      - historical-rates
      summary: Frankfurter Get Rates for a Time Period
      description: Returns historical rates for every day within a time period starting from the provided date until today.
      parameters:
      - $ref: '#/components/parameters/start_date'
      - $ref: '#/components/parameters/base'
      - $ref: '#/components/parameters/symbols'
      responses:
        '200':
          $ref: '#/components/responses/PeriodRateGetResponse'
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /{start_date}..{end_date}:
    get:
      tags:
      - historical-rates
      summary: Frankfurter Get Rates for a Time Period
      description: Returns historical rates for every day within a time period. The end date defaults to today if not provided.
      parameters:
      - $ref: '#/components/parameters/start_date'
      - $ref: '#/components/parameters/end_date'
      - $ref: '#/components/parameters/base'
      - $ref: '#/components/parameters/symbols'
      responses:
        '200':
          $ref: '#/components/responses/PeriodRateGetResponse'
        '404':
          $ref: '#/components/responses/NotFound'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
components:
  schemas:
    date:
      type: string
      format: date
      example: '2024-01-15'
      description: Date in YYYY-MM-DD format, all dates stored in UTC.
    ratesByDate:
      type: object
      description: Mapping of date → rates object
      propertyNames:
        $ref: '#/components/schemas/date'
      additionalProperties:
        $ref: '#/components/schemas/rates'
      minProperties: 1
      example:
        '1999-01-04':
          AUD: 1.91
        '1999-01-05':
          AUD: 1.8944
        '1999-01-06':
          AUD: 1.882
    base:
      type: string
      enum:
      - AUD
      - BGN
      - BRL
      - CAD
      - CHF
      - CNY
      - CZK
      - DKK
      - EUR
      - GBP
      - HKD
      - HUF
      - IDR
      - ILS
      - INR
      - ISK
      - JPY
      - KRW
      - MXN
      - MYR
      - NOK
      - NZD
      - PHP
      - PLN
      - RON
      - SEK
      - SGD
      - THB
      - TRY
      - USD
      - ZAR
      description: The base currency code following ISO4217
    baseIn:
      allOf:
      - $ref: '#/components/schemas/base'
      default: EUR
    rates:
      type: object
      description: Exchange rates keyed by currency code
      propertyNames:
        $ref: '#/components/schemas/base'
      additionalProperties:
        type: number
        exclusiveMinimum: 0
        multipleOf: 1e-05
      minProperties: 1
      example:
        AUD: 1.91
        CAD: 1.8004
        CHF: 1.6168
        CYP: 0.58231
    ratesOnDate:
      type: object
      properties:
        amount:
          $ref: '#/components/schemas/amount'
        base:
          $ref: '#/components/schemas/base'
        date:
          $ref: '#/components/schemas/date'
        rates:
          $ref: '#/components/schemas/rates'
      required:
      - base
      - date
      - rates
    amount:
      type: number
      description: The amount to convert
      exclusiveMinimum: 0
  parameters:
    start_date:
      name: start_date
      in: path
      required: true
      description: The start date for the period
      schema:
        $ref: '#/components/schemas/date'
    base:
      name: base
      in: query
      description: Base currency to convert from
      required: false
      schema:
        $ref: '#/components/schemas/baseIn'
    symbols:
      name: symbols
      in: query
      description: Comma-separated list of currencies to convert to
      required: false
      schema:
        type: array
        description: A list of currencies
        items:
          $ref: '#/components/schemas/base'
        minItems: 1
      explode: false
      example: USD,GBP
    end_date:
      name: end_date
      in: path
      required: true
      description: The end date for the period
      schema:
        $ref: '#/components/schemas/date'
  responses:
    NotFound:
      description: Resource not found
      content:
        application/json:
          schema:
            type: object
            properties:
              message:
                type: string
                example: not found
    PeriodRateGetResponse:
      description: Historical rates for the period
      content:
        application/json:
          schema:
            title: RatesDuringPeriod
            type: object
            properties:
              amount:
                $ref: '#/components/schemas/amount'
              base:
                $ref: '#/components/schemas/base'
              start_date:
                $ref: '#/components/schemas/date'
              end_date:
                $ref: '#/components/schemas/date'
              rates:
                $ref: '#/components/schemas/ratesByDate'
            required:
            - base
            - start_date
            - end_date
            - rates