What is using port 3000 on my Mac?

Port 3000 is the default for many dev servers: Node.js apps, Create React App, and Ruby on Rails all use it. A listener almost always means a development server you started. Run lsof -i :3000 to confirm.

Why is port 3000 still in use after I stopped my server?

A crashed or force-quit process can keep 3000 bound. Run lsof -i :3000 to find the leftover process and kill it.

Port 3000: What's Using It and Is It Safe to Kill?

Q: Is it safe to kill a process on port 3000?

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

Port 3000 is the default port for a long list of development servers. If something on your Mac is using it, that something is almost always a local web app you started.

What typically listens on port 3000

Node.js apps: Express and many other Node setups default to 3000.
Create React App: The React dev server starts on 3000.
Ruby on Rails: rails server defaults to 3000.
Next.js and others: A wide range of JavaScript frameworks pick 3000 out of the box.

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 3000 is something running on your own machine, not a macOS system service. Killing it frees the port and stops that server. Just confirm it isn’t a server you still need.

Is it suspicious?

On a development machine, no. Seeing 3000 in use is routine. It’s worth a look only if you don’t recognize the owning process and never run web servers. The command below shows the name.

How to find and free port 3000 on macOS

lsof -i :3000

To free it:

kill -9 $(lsof -ti :3000)

For the full walkthrough of the EADDRINUSE error, see Port 3000 already in use on Mac. Portie shows port 3000 with the app that owns it in its live list, and the $8.99 unlock lets you kill it from the row without Terminal.