Get the NBP exchange rate for a single currency vs PLN, on a specific date or the latest available. Table A = daily rates for major currencies (USD, EUR, GBP, CHF, JPY, etc.). Table B = twice-weekly rates for less common currencies. Table C = daily buy/sell rates (bid/ask) for major currencies — use for actual FX transactions, not accounting. For invoice-to-PLN conversion in Polish bookkeeping, use Table A. Note: NBP does not publish on weekends/holidays.

List all currency rates from an NBP table on a given date (or latest). Useful for seeing what's available and comparing multiple currencies at once.

Get the NBP exchange rate history for a currency over a date range. Range must be at most 367 days per NBP API limits.

Get the NBP gold fixing (cena złota) in PLN per gram of 1000-fineness gold, on a specific date or the latest. Published daily on business days.

Get NBP gold fixing history over a date range. Range must be at most 367 days per NBP API limits.

Convert an amount from one currency to another using NBP mid-rate (Table A, or B if not in A). Primary use case: converting a foreign-currency invoice to PLN for Polish bookkeeping. Polish tax law requires using the NBP mid-rate from the last business day BEFORE the invoice date — pass that date as rate_date, not the invoice date itself. Returns the amount, the rate used, and the effective date.