specification: API Commons Plans
specificationVersion: '0.1'
schema: https://raw.githubusercontent.com/api-evangelist/interface-research/main/schema/api-commons.yml#/$defs/Plans

provider: Frankfurter
providerId: frankfurter
created: '2026-05-29'
modified: '2026-05-29'
reconciled: true

tags:
  - Currency Exchange
  - Open Source
  - Free
  - Self-Hosted
  - MIT License

description: >-
  Frankfurter is a fully free, MIT-licensed open-source currency exchange API.
  The hosted public endpoint at api.frankfurter.dev requires no API key, no
  account, and has no monthly or daily caps. There are no tiers and no paid
  upgrades. The same code is distributable as a Docker image
  (lineofflight/frankfurter) for unlimited self-hosting at zero license cost;
  the only costs for a self-hosted deployment are infrastructure (compute,
  storage) and the operator's own time to register the optional, free
  upstream provider keys (Bank Al-Maghrib, Banco de México, Banco Central de
  Chile, Bank of Thailand, US Federal Reserve, Turkish Central Bank).

sources:
  - https://frankfurter.dev
  - https://frankfurter.dev/docs
  - https://github.com/lineofflight/frankfurter
  - https://github.com/lineofflight/frankfurter/blob/main/LICENSE

plans:

  - id: frankfurter-public-free
    name: Public Hosted (Free)
    type: freemium
    description: >-
      The public api.frankfurter.dev endpoint. No registration, no API key,
      no monthly or daily caps. Soft fair-use rate-limiting applies to
      protect the shared instance from abuse.
    entries:
      - label: API requests
        name: api_requests
        type: metered
        metric: request
        limit: -1
        timeFrame: month
        geo: global
        unit: 1
        price: '$0.00'
        userMultiplied: false
      - label: API key
        name: api_key
        type: flat
        metric: account
        limit: 0
        timeFrame: usage
        geo: global
        unit: 1
        price: 'not required'
        userMultiplied: false
      - label: Fair-use rate limiting
        name: fair_use_rate_limit
        type: quota
        metric: varies
        limit: 'soft / undocumented'
        timeFrame: second
        geo: global
        unit: 1
        price: '$0.00'
        userMultiplied: false
    elements:
      - name: Latest blended rates across 50+ central banks
      - name: Historical rates back to 1948
      - name: Time-series queries with optional week/month downsampling
      - name: 201 currencies
      - name: JSON, NDJSON, and CSV output formats
      - name: Open CORS for browser access

  - id: frankfurter-self-hosted-foss
    name: Self-Hosted (FOSS)
    type: subscription
    description: >-
      Run your own Frankfurter instance from the public Docker image. MIT
      license — no license fee, no per-call charge, no telemetry. You pay
      only for the infrastructure you provision and the optional provider
      API keys you choose to register (all of which are themselves free).
    entries:
      - label: Software license
        name: license_fee
        type: flat
        metric: month
        limit: -1
        timeFrame: month
        geo: global
        unit: 1
        price: '$0.00 (MIT)'
        userMultiplied: false
      - label: Per-call cost
        name: per_call_fee
        type: metered
        metric: request
        limit: -1
        timeFrame: month
        geo: global
        unit: 1
        price: '$0.00'
        userMultiplied: false
      - label: Infrastructure
        name: infrastructure
        type: flat
        metric: varies
        limit: 'operator-provisioned'
        timeFrame: month
        geo: global
        unit: 1
        price: 'see your cloud provider'
        userMultiplied: false
      - label: Optional upstream provider keys
        name: upstream_provider_keys
        type: flat
        metric: varies
        limit: 6
        timeFrame: usage
        geo: global
        unit: 1
        price: '$0.00 (each issued free by the relevant central bank)'
        userMultiplied: false
    elements:
      - name: Full OpenAPI v1 and v2 endpoint surface
      - name: SQLite storage with optional persistent volume
      - name: Docker image at lineofflight/frankfurter
      - name: Optional provider keys for Bank Al-Maghrib, Banco de México, Banco Central de Chile, Bank of Thailand, US Federal Reserve, Turkish Central Bank
      - name: Full source code on GitHub under MIT