Historical exchange rate data via World Bank API? I can see a massive list of indicators available via the World Bank API here (may take 1-2 minutes to load)
I found exchange rates for various currencies into USD, but cannot see how to get exchange rates between currencies which aren't the USD.
Is this possible via the World Bank API?
I don't think so, since:

USD is usually used as a reference.
Providing exchange rates for all possible pairs would be to much data. If there are 100 countries, there would be 100! (factorial) different pairs.
Exchange rates for all different pairs can be calculated manually by using the USD rates of two pairs.