Which currencies are real-time

Every response is stamped with its source, so you always know what you got. 16 currencies are real-time (updated about every 60 seconds through the trading week). 14 are ECB daily-reference — updated once per business day at ~16:00 CET; between fixes the rate does not update, and they carry Friday's fix through the weekend. A pair is only as fresh as its slowest leg, so any pair containing a daily-reference currency is daily-reference too.