How to check where the get request from the site goes?

Question

URL Handling

Good day to all! The question is slightly twisted, but still, help someone please!
There is a site, it takes some data from somewhere (with the help of what and from where I don’t know, but I want to understand), the essence of the site is such that parameters are set there, the amount of data given, some parameters of the data itself, etc., then the "find" button is pressed and the site returns the result of the data search. I want to understand where he gets them from, obviously not from himself, but let's say by API, I checked the request that generates the site when I click on the "find" button and it gives me a get request (but this is my request to the site), it goes like site.com /primer/index?data1&data2.......... how can I figure out where this request goes next? Tobish data source
Prompt please!!!

Answer 1

Study the website code. For example, look for occurrences of http and https, maybe you will stumble upon an external request. Or .com/ .net/ .org/ .ru/
If you have access to the server, see connections, logs.
In the end, you can google "where to get / download ...", "API ..." and further details related to your data. Maybe you can find a source.