Base and quote currency explained
Read a currency pair in the right direction, invert an exchange rate, and interpret the base and currency fields in an FX API response.
FX API guides
Practical guidance for exchange-rate history, freshness, and implementation.
How currency conversion works
Convert an amount using an exchange rate, handle the reverse direction, and distinguish a reference conversion from a payout after fees.
Exchange-rate precision and rounding
Keep decimal exchange rates accurate, round monetary results once, and understand half-even rounding with reproducible Python examples.
Cross rates explained
Calculate a currency cross rate from two rates with a shared base, check the direction, and avoid mismatched timestamps or rounding inputs too early.
Exchange rate timestamps and freshness
Distinguish observation time from request time, read stale and market-session fields, and design a freshness check for an exchange-rate application.
How historical exchange rates work
How Narwhal returns real observation dates, sparse currencies, and bounded FX history pages.
How exchange-rate APIs handle weekends
How market session, timestamps, and stale state explain an FX rate when markets are closed.