The exchange rate processors that we have/had (Yahoo Finance, Google Finance, etc.) can be unreliable as they may scrape a website for the exchange rate (and the page can change, breaking the scrape), the accuracy may not be accurate, or in the case of Yahoo Finance, the service can be discontinued abruptly without notice.

It would be better to also support a dedicated exchange rate processing service that provides an API and API key for fetching rates. These services can require a paid subscription, so they should be added in addition to the free (but potentially unreliable) ones that currently exist in Blesta. Because of the necessity to support an API key, exchange rate processors should be able to inject a set of fields to save as settings for the processor.

Consider the following new exchange rate processors:

1. Currency Layer
   • Free version supports up to 1000 API calls per month, updated hourly
2. Open Exchange Rates
   • Free version supports up to 1000 API calls per month, updated hourly.
   • Free version is LIMITED TO USD AS BASE CURRENCY! We may be able to work-around this by converting the rate with respect to the base currency configured in Blesta.
3. European Central Bank
   • Data is provided via XML on a daily work-day-basis after 4 PM CET
   • XML available @ http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml
   • CURRENCIES ARE LIMITED
4. Fixer.io (CORE-2536)
   • Example: http://api.fixer.io/latest?base=USD
   • CURRENCIES ARE LIMITED
5. X-RATES (CORE-2534)
   • Example: http://www.x-rates.com/calculator/?from=GBP&to=USD&amount=1
   • CURRENCIES ARE LIMITED