For the Magento 2 Fixer.io integration see my repo over here: https://github.com/philwinkle/Philwinkle_Fixerio-M2
This module adds the Fixer.io webservice to the list of available currency conversion webservices in Magento.
To enable navigate to System > Config > Currency Setup and select Fixer.io from the dropdown. Ensure that your shop is set to allow multiple currencies by, of course, selecting multiple currencies from the allowed currencies setting.
Now navigate to System > Manage Currency > Rates.
Select Fixer.io from the dropdown and select "Import" to begin an import. You will need to save the data values after run by clicking "Save" in the upper-right hand corner.
Import the rates nightly by setting up the job to do so. Navigate to System > Config > Currency Settings > Scheduled Import Settings and select Fixer.io from the dropdown. Also enable the service if not previously enabled.
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