Localhost11501 Exclusive ((free)) -

using (HttpListener listener = new HttpListener())

const net = require('net'); const server = net.createServer(); server.listen(11501, '127.0.0.1', () => console.log('Exclusive bind on port 11501'); ); // No special flag needed on most OS—default is exclusive. localhost11501 exclusive

tasklist | findstr <PID> If you see SYSTEM or a specific app, that process has an exclusive bind. sudo lsof -i :11501 Or: using (HttpListener listener = new HttpListener()) const net