Port 4200: What's Using It and Is It Safe to Kill?

Port 4200 is the default port for the Angular CLI dev server. A listener on 4200 is almost always ng serve running a local Angular project.

What typically listens on port 4200

Angular CLI: ng serve defaults to 4200.
Angular-based tooling: Some Angular project templates and tools reuse it.

It’s in the registered range (1024-49151), so any app can bind it without admin rights.

Is it safe to kill?

Yes. A process on 4200 is a local dev server, not a macOS service. Killing it frees the port and stops that server. Confirm it isn’t one you still need.

Is it suspicious?

On a development machine, no. It’s a routine front-end dev port. Worth identifying only if you don’t recognize the owning process and don’t work with Angular.

How to find and free port 4200 on macOS

lsof -i :4200

To free it:

kill -9 $(lsof -ti :4200)

Portie shows port 4200 with the app that owns it in its live list, so you can clear a stuck Angular server in seconds.

Common questions

What is using port 4200 on my Mac?

Port 4200 is the default for the Angular CLI dev server. A listener means ng serve is running. Run lsof -i :4200 to confirm.

Is it safe to kill a process on port 4200?

Yes. It's a local Angular dev server, not a macOS service. Killing it frees the port and stops that server without affecting the system.

How do I run Angular on a different port?

Use ng serve --port 4201 (or any free port). Freeing 4200 lets ng serve return to its default.