Frankfurter Rate API

openapi: 3.2.0
info:
  title: Frankfurter Rate API
  description: Frankfurter is an open-source API for current and historical foreign exchange rates published by central banks.
  version: 2.1.1
  license:
    name: MIT
    url: https://github.com/lineofflight/frankfurter/blob/main/LICENSE
  contact:
    url: https://github.com/lineofflight/frankfurter/issues
servers:
- url: https://api.frankfurter.dev/v2
tags:
- name: Rate
paths:
  /rate/{base}/{quote}:
    get:
      operationId: getRate
      summary: Get a single exchange rate pair
      description: Returns the blended exchange rate for a single currency pair. Without a date param, returns the latest rate. A same-currency pair returns the identity rate of 1.
      parameters:
      - name: base
        in: path
        required: true
        schema:
          type: string
          example: EUR
      - name: quote
        in: path
        required: true
        schema:
          type: string
          example: USD
      - $ref: '#/components/parameters/date'
      - $ref: '#/components/parameters/providers'
      responses:
        '200':
          description: Exchange rate
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Rate'
              example:
                date: '2026-03-25'
                base: EUR
                quote: USD
                rate: 1.1568
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '404':
          $ref: '#/components/responses/NotFound'
        '503':
          $ref: '#/components/responses/ServiceUnavailable'
      tags:
      - Rate
components:
  parameters:
    date:
      name: date
      in: query
      description: Specific date (YYYY-MM-DD). Cannot be combined with from/to.
      required: false
      schema:
        type: string
        format: date
        example: '2024-01-15'
    providers:
      name: providers
      in: query
      description: Comma-separated list of data providers to include. A single provider includes its stored non-currency series. Selecting multiple providers blends only registered currencies and accounting units.
      required: false
      schema:
        type: string
        example: ECB,TCMB
  responses:
    ServiceUnavailable:
      description: 'The request deadline expired before the response could be computed, or the worker process is already running its limit of concurrent live daily-range computes (any daily range served live: with providers, with expand=providers, or before the precomputed blend is ready). In the second case a Retry-After header says how many seconds to wait before retrying. Otherwise retry with a narrower request: filter with quotes, aggregate with group, or split the range into shorter requests.'
      headers:
        Retry-After:
          description: Seconds to wait before retrying. Sent when the server is at its limit of concurrent daily range computes.
          schema:
            type: integer
      content:
        application/json:
          schema:
            type: object
            properties:
              message:
                type: string
    UnprocessableEntity:
      description: Invalid request
      content:
        application/json:
          schema:
            type: object
            properties:
              message:
                type: string
    NotFound:
      description: No data found
      content:
        application/json:
          schema:
            type: object
            properties:
              message:
                type: string
  schemas:
    Rate:
      type: object
      properties:
        date:
          type: string
          format: date
          description: The date of the rate
        base:
          type: string
          description: Base currency or accounting unit code
        quote:
          type: string
          description: Quote currency or accounting unit code
        rate:
          type: number
          description: Exchange rate value
          exclusiveMinimum: 0
        providers:
          type: array
          description: 'Per-provider rates for this pair. Present only when `expand=providers` is set. Each entry has the provider''s observation date and published rate (rebased to the row''s base). Entries with `excluded: true` did not contribute to the blended `rate` — either flagged as outliers by the consensus filter, or overridden by a currency peg. A one-day typo in a provider''s series is left out, so its entry shows the observation before it. Omitted on synthesized peg rows where no provider published the quote.'
          items:
            type: object
            properties:
              key:
                type: string
                description: Provider key
              date:
                type: string
                format: date
                description: Provider observation date used for this entry
              rate:
                type: number
                exclusiveMinimum: 0
                description: Provider's rate, rebased to the row's base
              excluded:
                type: boolean
                description: Present and true when this entry did not contribute to the blended rate
            required:
            - key
            - date
            - rate
      required:
      - date
      - base
      - quote
      - rate