FX History API
Live historical foreign-exchange rates and analytics from the European Central Bank's daily reference rates — no key, nothing cached. Get the daily rate of a currency pair over any date range; the absolute and percentage move between two dates with its high and low; min, max, average, volatility and the best and worst day over a range; and every rate on a specific date. An FX history-and-analytics layer, distinct from spot-conversion feeds — it turns the ECB rate archive into the time series, moves and volatility a trader or analyst studies. Around 30 currencies, weekdays, back to 1999.
api.oanor.com/fxhistory-api