I need to develop an app that intercepts HTTPS traffic on the machine and change it. One approach is to use a local proxy, like Fiddler works.

I also saw HTTP Debugger (https://www.httpdebugger.com/) which works in a similar way to Fiddler but say they don't use a proxy.

Do you know what technology HTTP Debugger are using in order to intercept HTTPS traffic without proxy?