localhost:8443: what runs on it and how to open it
Port 8443 is the usual second HTTPS port. See what runs on it, why the browser warns, and how to open it.
Open this address: http://localhost:8443This opens on your own computer. It only works if the program is running.
localhost:8443 is the usual alternate HTTPS port. Programs that cannot or should not use port 443 often use 8443, so open it with https:// in front.
What runs on localhost:8443
- Java servers such as Tomcat or Spring Boot set up for HTTPS
- Plesk and similar control panels
- UniFi Network software on older versions
- Any web server you start with TLS on a port other than 443
Commands to start and test port 8443
curl -k https://localhost:8443openssl s_client -connect localhost:8443 </dev/nulljava -jar app.jar --server.port=8443Find what is using port 8443
Run these in a terminal on your computer. Nothing is sent to this site.
If localhost:8443 will not open
- The browser warns that the connection is not private
- A local server usually has a self-signed certificate that no browser trusts. On your own computer you can continue past the warning. Do not do this for a website on the internet.
- The page asks for http but needs https
- Port 8443 normally speaks HTTPS. Type https://localhost:8443, not http.
- Port 8443 is already in use
- Another program is on this port. Find it with the tool below and stop it, or start yours on another port.
- This site can’t be reached (ERR_CONNECTION_REFUSED)
- The program is not running. Start it and keep that terminal open. See the full checklist.
- Works on your computer, not on your phone
- Start the server on all network addresses and use your computer’s IP address. See how to open localhost from your phone.
Other ports like 8443
| 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:8888 | Jupyter Notebook |
Questions about localhost:8443
- Why https and not http?
- Port 8443 is conventionally used for TLS. If you type http, the server often answers with an error or nothing.
- Is localhost:8443 safe?
- Yes, as long as it stays on localhost. Only your own computer can reach it. It becomes reachable from other devices only if you start the program on 0.0.0.0 or your computer's IP address. Do not put development or admin tools on the public internet.
- Can I use a different port instead of 8443?
- 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.
- How do I check what is using port 8443?
- 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:8443 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 the port 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.