Port 8888: Jupyter / HTTP alternate
Port 8888 is the default for Jupyter Notebook and a common alternate web and proxy port.
What runs on port 8888
Jupyter Notebook and JupyterLab serve their interface on TCP 8888 by default, letting you run Python code from a browser. Many proxies and admin tools also use 8888 as an alternative to 8080.
On a home network
Laptops and home servers used for data science or learning Python run Jupyter on 8888. Some routers and media tools use it for a web interface.
If port 8888 is reachable from the internet
An exposed Jupyter server is a remote code execution service by design: anyone who reaches it and passes its token or password can run any command. Instances started with authentication turned off are found and abused, often to run cryptominers. Keep Jupyter on localhost and reach it through an SSH tunnel or VPN.
How to check whether it is open on your network
When starting Jupyter, check that it binds to localhost and uses a token or password. A LAN port scan shows which machines serve 8888.
To find out whether port 8888 is open on something in your home, and whether the internet can reach it, the app scans your Wi-Fi from your phone and checks your public address from the outside. It says what it checked and what it could not. Get RECON for iPhone — one-time purchase, no account, nothing leaves the device.