I’m developing a web application which is required to call a custom registered protocol

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Asked: June 1, 20262026-06-01T14:06:48+00:00 2026-06-01T14:06:48+00:00

I’m developing a web application which is required to call a custom registered protocol

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I’m developing a web application which is required to call a custom registered protocol on the clients computer. Currently I do a GET to the protocol, which then passes the parameters via the querystring.

Is it possible to do a POST to a custom registered protocol and if so how would I go about extracting the header information within CustomProtocol.exe?

This is my current GET solution

To Initiate the call from javascript

Custom://startup?Function=DoSomething&Value1=Test&Value2=Test

The custom protocol that I registered onto my machine.

[HKEY_CLASSES_ROOT\Custom\shell\open\command]
@="\"CustomProtocol.exe\" \"%1\""

I then compiled the below code to generate the CustomProtocol.exe. During execution the URI is passed into the Main method, I then extract the querystring.

namespace CustomProtocol
{
    class Program
    {   
        static void Main(string[] args)
        {
           // Get the querystring from the URI being passed in
           // Business code...
        }
    }
}

EDIT 1:

This is the header when doing a post to the custom registered protocol. The protocol only has 1 arg passed into it just like the GET which is the URI. Somehow if I only were able to access the header information…

Request URL:http://localhost/CustomWebInvoker/Default.aspx Request Headersview source Accept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Content-Type:application/x-www-form-urlencoded Origin:http://localhost Referer:http://localhost/CustomWebInvoker/Default.aspx User-Agent:Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.78 Safari/535.11 Form Dataview URL encoded
        __VIEWSTATE:/wEPDwUKMTkxMDU5NzI4OWRkBWZZppW219Muku6ZjiGZLQG5um8=
        __EVENTVALIDATION:/wEWCwKz9d77DAK57evuBgLk0vuTDALl+pjzDQKB8r3PAQKk+8X1CwLLneGNCgK2gO/LCAK355HvBAKAseegDAL+ovbYDMmmPuTHB0XbFjGRG9Wl1ij5kObV 
    dlLanguage:English  
    dlApplicationMode:UpdateMode 
    dlCallingApplication:CSS  
    dlCentre:EasternCompCenter  
    btnFastPath:Fast Path