Best practices
Batch processing
When batch processing transactional data, use the Time Series endpoints to retrieve exchange rates for a larger interval and cache these values on the client side for optimal performance. The maximum query interval is 180 days.
Avoid repeated calls to access the same data, as this can quickly result in hitting an API rate limit.
Daily updates
When updating your local database daily, always check for rates that may have been published by the bank with a delay and thus missed by your previous update. TIP: Use the Time Series endpoint with a start date a few days before the current day and compare the data returned with your local database.
Do not rely solely on the daily bank update times and holidays as they are for reference only. Accuracy may vary by country/bank.
Monthly updates
Banks or tax authorities that publish monthly rates for a given month on or before the first day of that month (such as HMRC) may publish amendment rates later if there is a significant change in the exchange rates during the month. You should therefore check regularly for changes to monthly rates.