Source

The European Central Bank Statistical Data Warehouse — sdw.ecb.europa.eu. These are the same daily reference rates the ECB publishes for accounting and statistical use across the Eurosystem.

Cadence

Fetched daily at 09:00 UTC via the Frankfurter.app proxy, which mirrors the ECB feed without rate limits. A failed fetch triggers an admin alert; the previous day's rate is reused until the next successful sync.

Policy

Mid-market rate only. WorthOf does not apply a retail FX spread, card fee, or bank margin. Real-world conversions you make at a bank or remittance service will usually be 1–3% worse than these figures.

API call

GET https://api.frankfurter.app/latest?from=EUR

→ {
    "amount": 1.0,
    "base": "EUR",
    "date": "2026-01-15",
    "rates": { "USD": 1.0842, "GBP": 0.8421, "PLN": 4.2710, ... }
  }

Rates are stored in fx_rates with EUR as the base currency; cross-rates (e.g. USD→GBP) are derived at query time.