I thought it would be a very common dataset: world exchange rates at daily frequency for every currency pair (or each currency's rate vs USD so triangulation can fill in for every other rate)
But apparently it's not so easy to find. I tried the World Bank API (it's massive, and it may be there, but I can't find a specific endpoint that provides it), and the IMF (they have data explorers but no forex API AFAIK).
As this must be a very interesting time series dataset, I figured it would be easy to find, but I cannot locate it.
strong preference for a completely open/public API (one that doesn't require keys)