Your website looks good. The examples in several languages is also a nice touch (expected from API documentation).

I do have plenty of questions though.

Does this service get historical rates from its sources in real time or does it store those in its own local database?

How long will this service be free for? What’s the business model that’s being thought about?

What kind of rate limiting, if any, is used so that a developer who uses these APIs doesn’t have their app go down because someone else is hammering the server with a lot of requests?