How to: Identify which application is listening or opening a specific port on Windows

1. Open Command Prompt window by typing Cmd in Run command box or Start Search, and hit Enter.
2. Type in the following netstat command:

netstat -o -n -a | findstr :80

or

netstat -aon | findstr :443

Where the text after findstr is the text you want to find in the list of netstat. For example, in the first one you´ll find who has the port 80 open while on the second one you´ll find who is listening on port 443.