localhost:8888: what runs on it and how to open it
Port 8888 is Jupyter’s default and an older MAMP default. How to open it and fix token and connection problems.
Open this address: http://localhost:8888This opens on your own computer. It only works if the program is running.
localhost:8888 opens Jupyter Notebook or JupyterLab by default. Older MAMP installs also use it for Apache.
What runs on localhost:8888
- Jupyter Notebook and JupyterLab
- Older MAMP versions (Apache on 8888, MySQL on 8889)
Commands to start and test port 8888
jupyter labjupyter notebookjupyter lab --port 8889jupyter server listFind what is using port 8888
Run these in a terminal on your computer. Nothing is sent to this site.
If localhost:8888 will not open
- Jupyter asks for a token or password
- Copy the full URL with ?token= from the terminal, or run
jupyter server list. - MAMP page will not load
- Start the servers in MAMP first. In MAMP preferences you can set Apache to port 80 and MySQL to 3306.
- jupyter: command not found
- Install it with
pip install jupyterlaband activate the right Python environment.
Other ports like 8888
| Port | Usually used by |
|---|---|
| localhost:3000 | React, Next.js, Express |
| localhost:5173 | Vite dev server |
| localhost:4200 | Angular dev server |
| localhost:5000 | Flask |
| localhost:8000 | Django, PHP, Python |
| localhost:8080 | Tomcat, Spring Boot, Docker |
| localhost:9000 | PHP-FPM, SonarQube |
Questions about localhost:8888
- What is localhost:8888?
- The default port of Jupyter Notebook and JupyterLab, and of Apache in older MAMP versions.
- Why does Jupyter ask for a token?
- Jupyter protects access with a token. Copy the full URL from the terminal, or run jupyter server list.
- Is localhost:8888 safe?
- Yes, as long as it stays on localhost. Only your own computer can reach localhost:8888. It becomes reachable from other devices only if you start the program on 0.0.0.0 or your computer's IP address. Development servers are for testing, so do not put them on the public internet.
- Can I use a different port instead of 8888?
- Yes. Most programs let you choose the port with a setting or a command option. Pick a free port above 1024 and open that number instead, for example localhost:8889.
- How do I check what is using port 8888?
- Use the port checker on this page. It shows the command for Windows, macOS and Linux and does not send anything to this site.
- Can I open localhost:8888 from my phone?
- Yes, if both are on the same Wi-Fi. Start the program so it listens on all addresses, then open your computer's IP address with :8888 on the phone. A firewall on the computer can still block it.
Free tools that help
- Common ports listSearch a list of common TCP and UDP port numbers: SSH 22, HTTP 80, HTTPS 443, MySQL 3306, PostgreSQL 5432 and more, with dev server ports.