确定网站系统的源代码

Ok, in work I use a particular system to look up part numbers for products. It's accessed in the browser and can only be accessed by company machines and I have a log on to use the system. Once logged in, I type in the part number and it prints a list into a rich text field with the part number, serial number, description and some other bits of info. It doesnt have the ability to search for multiple part numbers, so I literally have to type in the first, wait for the result, then the second, etc. What I'm looking to do is write some code that will loop through a text file and print out part of the result into the text file next to each part number. This kind of code I'm used to.

My problem however is that I dont know what the source code / function is for this company owned system. If I view the source I cant see a js file or anything similar with what I would think the script would live in, so assume its server side. If I watch the requests, I can see the parameters being passed, but I dont know how I could recreate this in code and obtain a result. Would be nice if it spat out some json, but I dont think its that easy :-)

Any pointers to get me going and areas I should look at?

Thoughts appreciated.

You can view the response headers in the browser's network tab, if it's php, by default it adds a header that you'll recognize.

But, how will you deploy your server side code if you don't have access to the server? And if you do, then why do you need to guess the language like this?