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.

OANDA - OANDA is an advanced forex and broker trading platform that helps you in currency data, exchange rate services for the investors and organizations.

ExchangeRate-API - An easy to use, free & reliable Exchange Rate API trusted by tens of thousands of developers since 2010!

FXOpen - FXOpen is a forex and cryptocurrency trading solution that manage the PAMM account and provides all backup with analytics and customer support.

xChangeApi - Easy to use, free live updated foreign exchange rates API

Avatrade - Avatrade is an online and advanced FX & CFD broker that provides personal investment and trading facilities with the help of currency pairs, cryptocurrencies, commodities & indices as well.