Daily European Central Bank reference rates for 30 currencies: latest rates against any base, conversion (latest or on a date), history back to 1999 and time series.
The Currency Exchange Rates API serves the European Central Bank's euro foreign exchange reference rates, published once per working day around 16:00 CET, for 30 major currencies. Any currency can be the base (cross rates through the euro). /convert converts an amount to one or several currencies at the latest rate or the rate of a past date; weekends and TARGET holidays fall back to the previous publication and both dates are returned. /historical returns the full set for any date since 1999-01-04 (including currencies the ECB no longer quotes, for dates when they were quoted). /timeseries returns daily rates for up to a year. Every response names the source. Reference rates are for information; for trading or settlement use your bank's rate.
https://apistack.online/api/finance/currency-exchange-rates/v1finance