How do I get exchange rates by date?

Question

I am interested to find exchange rates by a certain date. Do you guys know what API I can use for this? (Preferably, a free API.)

I create an object with creation date the 20th of May, 2016. That object has a price in EUR. I want to be able to get the exchange rate of EUR to USD for that date and convert it to USD.

Answer 1

It seems like fixer.io should suit your needs:

http://fixer.io/

Your example:

http://api.fixer.io/2016-05-20?base=EUR&symbols=USD

Note that apparently your referrer header can make you get a 403 response. (so copy and paste this link in the browser, don't click on it - thanks @Arnauld)