What is using port 8888 on my Mac?

Port 8888 is the default for Jupyter Notebook and JupyterLab. A listener usually means a Jupyter server is running. Run lsof -i :8888 to confirm.

Is it safe to kill a process on port 8888?

Yes for macOS, but you'll lose any unsaved notebook state. Prefer shutting Jupyter down from its interface or with jupyter notebook stop, then kill the PID only if it's stuck.

Why does Jupyter open on 8889 sometimes?

If 8888 is already in use, Jupyter increments to 8889, 8890, and so on. Freeing 8888 lets it use the default again.

Port 8888: What's Using It and Is It Safe to Kill?

Port 8888 is the default port for Jupyter Notebook and JupyterLab. A listener on 8888 usually means a Jupyter server is running locally.

What typically listens on port 8888

Jupyter Notebook / JupyterLab: Both default to 8888.
Other data-science tools: A few notebook-style tools reuse it.

If 8888 is taken, Jupyter moves to 8889 and up, which is why you sometimes land on a higher port. It’s in the registered range (1024-49151).

Is it safe to kill?

For macOS, yes. The caution is unsaved work: killing the process drops any notebook state that hasn’t been saved. Shut it down cleanly first:

jupyter notebook stop 8888

Then kill the PID only if the server is genuinely stuck.

Is it suspicious?

On a machine where you run notebooks, no. Worth identifying only if you don’t recognize the owning process and don’t use Jupyter. The command below names it.

How to find and free port 8888 on macOS

lsof -i :8888

To free it:

kill -9 $(lsof -ti :8888)

Portie shows port 8888 with the app that owns it in its live list, so you can confirm a Jupyter server is running and clear it if it gets stuck.