ExchangeRate-API.com offers an easy-to-use JSON currency conversion API with unlimited free requests. The service supports all 160 major currency codes and an incredibly accessible API request format. ExchangeRate-API has been a popular option for developers to get exchange rate data since 2010!
exchangeratesapi.io - Foreign exchange rates API with currency conversion.
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Fixer.io - Fixer provides a free, simple, and lightweight API for current and historical foreign exchange rates and currency conversion. The API tracks rates published daily by the European Central Bank.
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Open Exchange Rates - Free, hourly-updated exchange rates - a simple, accurate, open-source JSON API. Free for personal use, a bargain for everybody else.
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