check which program is using a port code example

Example 1: linux query port use by pid

$ sudo netstat -nlp | grep :80
tcp  0  0  0.0.0.0:80  0.0.0.0:*  LISTEN  125004/nginx

Example 2: check which application is using port

In Windows CMD/Powershell:
netstat -aon | findstr '[port_number]'