How to create or where to get this kind of api?

Question

API

How to create or where to get this kind of api like monitoring exchange offices? For example, bestchange, when choosing an exchange of some currency, shows what exchange rate the exchangers have, and in general, where can I get this api or how to create a target like this monitoring?

Answer 1

How to create - write a technical specification and hire a programmer.
How to get this api - read faq bestchange, it says how.