US Treasury Rates of Exchange API
The official US government foreign-exchange rates, served live from the US Treasury's FiscalData API — no key, nothing cached. These are the rates the federal government uses to convert foreign-currency balances into US dollars for reporting, and US companies use them for tax and compliance; they are published every quarter for around 168 currencies and go back two decades. The rates endpoint returns the whole quarterly set — every country and currency with its rate to one US dollar (the euro near 0.87, the yen near 159) — and accepts a date to pull any past quarter. The currency endpoint returns one currency's official rate with its history quarter by quarter, looked up by ISO code, country or currency name. The convert endpoint turns an amount from any currency into any other, crossed through the US dollar at the official Treasury rate. Everything is the Treasury's own published data, live, nothing stored; rates are quarterly and authoritative for accounting, not a live market quote. This is the official FX layer for any accounting, tax-compliance, treasury, government-contracting or historical-FX app. Distinct from central-bank and market FX APIs — this is the US Treasury's quarterly reporting rates of exchange. 4 endpoints, no key on our side.
api.oanor.com/treasuryfx-api
