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.
ActTrader - ActTrader - The leading edge of currency trading technology
FxPro - FxPro offers web and mobile based online trading platforms and tools.
ExchangeRate-API - An easy to use, free & reliable Exchange Rate API trusted by tens of thousands of developers since 2010!
e2eFX - Nexolink is a Toronto based foreign exchange software developer specializing in services for the small to large size FX broker and FX Global Payment Businesses .
Xone Trader - Forex Exchange and Trading