Port 4200 is already in use. Use ‘–port’ to specify a differ

For angular

 

You can change your application port by entering the following command,ng serve --port 4200Also, for a permanent setup you can change the port by editing angular-cli.json file"defaults": {"serve": {"port": 8080}}

 

For nodejs

 

var http = require('http'); http.createServer(function (req, res) {res.writeHead(200, {'Content-Type': 'text/plain'});res.end('Hello World\n'); }).listen(8124, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8124/');