TY.  Have done investigation and found following; Fixer (Free) Base currency MUST be EUR https://fixer.io/documentation - "Exchange rates delivered by the Fixer API are by default relative to EUR." Fixer (paid) Base currency can be any supported.   CurrencyLayer (Free) Base currency MUST be USD https://currencylayer.com/documentation#source_currency_switching CurrencyLayer (paid) Base currency can be any supported.   ExchangeLayer (new coded,