Yahoo source

[hkdobrev]

Yahoo provides a free API for exchange rates.

Unlike European Central Bank though, it gives a list of currency pairs.

You could get all currencies at once or ask for specific pairs (on different endpoints though).

[yanev]

As far as I remember Yahoo Finance API had some limitations (returning invalid response when the server is overloaded) which happens very often :) I think the Open Exchange Rates would be a better solution.

[hkdobrev]

I started implementing the Yahoo source (similar to the old finance service), but I had several issues.

• Yahoo Finance API is for finances news only.
• They have a quote API (for stocks) which supports currencies as well (CSV-only).
• Using YQL you could extract currency pairs of exchange rates (XML).
• They have another API with all of the currency data in a different XML format, but still paired.
• Not available detailed documentation for any of that.

So I decided to leave it for some better times when I would have more time or the Yahoo dev team would come up with one documented way of providing currency data.