Historical ECB exchange rates — single date lookup or time-series range. Returns rates for up to 30 major currencies (EUR, GBP, JPY, CAD, CHF, CNY, AUD, KRW, etc.) from 1999-01-04 to present. Free, no key, sourced from Frankfurter/ECB. Use for: tax-date FX rates, historical expense reconciliation, multi-year trend analysis, point-in-time currency conversion. Weekends and holidays return the nearest prior business day. Complements forex-rates (real-time) with retrospective data.