API & balance of ETH accounts?

I would like to programmatically find out the balance of an ETH account.

How does a WebApp interact with an API? Totally new at this API thing so I don’t understand how exactly they work.

By ETH you are referring to ethereum, I guess?

Get an access key and more info about its api here:

Here a general example on how to use a webservice from xojo:

Or read this Xojo blog articles: