Frankfurter

Overview

Frankfurter is a free, open-source currency API that tracks reference exchange rates published daily by the European Central Bank (ECB) — 30+ currencies, no API key, no registration, no rate limit for reasonable use. Perfect for price displays, invoicing, and multi-currency widgets.

⚠️ Domain migration (verified 2026-08): the API now lives at api.frankfurter.dev/v1 — the old api.frankfurter.app host redirects (301) to the new one. Update your endpoints accordingly.

Quick Start

Latest EUR↔USD rate (verified live on the new domain):

curl "https://api.frankfurter.dev/v1/latest?from=USD&to=EUR"

{"amount": 1.0, "base": "USD", "date": "2026-08-21", "rates": {"EUR": 0.85477}}

All rates for a base currency:

curl "https://api.frankfurter.dev/v1/latest?from=USD"

Historical rate on a specific date:

curl "https://api.frankfurter.dev/v1/2024-01-15?from=USD&to=EUR"

Rate range between two dates:

curl "https://api.frankfurter.dev/v1/2024-01-01..2024-01-31?from=USD&to=EUR"

List supported currencies:

curl "https://api.frankfurter.dev/v1/currencies"

Authentication

None — keyless, registration-free.

Rate Limits & Notes

• Free for reasonable use; no hard documented limit (respect the service — it’s run openly by volunteers).
• Rates are the ECB’s daily reference rates (published on ECB business days).
• amount in the response lets you do conversion in one call: ?amount=100&from=USD&to=EUR.
• Old hosts (api.frankfurter.app) still respond but redirect — switch to .dev to avoid extra hops.

FAQ

Is Frankfurter free? Yes — free, keyless, no registration.

Where does the data come from? Daily reference rates from the European Central Bank.

What changed with the domain? The API moved from api.frankfurter.app to api.frankfurter.dev/v1 — the old host 301-redirects.