Port 80 (HTTP)
Port 80 is plain HTTP, the unencrypted web. Browsers use it when an address starts with http://; today most sites only answer on 80 to redirect visitors to HTTPS on port 443.
- Service
- HTTP
- Protocol
- TCP
- IANA registry
- Officially assigned: http (World Wide Web HTTP), TCP/UDP
Check if a port is open on your IP
We only check the address you are visiting from, one TCP port at a time. You cannot enter someone else’s address: this is not a port scanner.
Is it safe to open port 80?
Traffic on port 80 can be read and changed by anyone on the path, so do not serve logins or personal data over it. Keep 80 open only to redirect to HTTPS and to pass ACME HTTP-01 challenges when issuing certificates.
Sources
“Port 80 is already in use”: how to fix it
The error means another program is already listening on port 80. Find its process ID (PID), then stop that program or start yours on a different port.
Windows (Command Prompt or PowerShell as administrator)
netstat -ano | findstr :80taskkill /PID <PID> /FmacOS
lsof -nP -iTCP:80 -sTCP:LISTENkill <PID>Linux
sudo ss -ltnp | grep :80sudo lsof -i :80sudo kill <PID>Replace <PID> with the number from the last column (Windows) or the PID column (macOS, Linux).
Port 80 vs 443
Port 80 is HTTP without encryption; 443 is HTTPS with TLS. A modern site serves everything on 443 and keeps 80 only to redirect visitors there.
Port 443 (HTTPS)Why a port can look closed when your server is running
Most home networks sit behind a router doing NAT: the router owns the public address, and your computer has a private one such as 192.168.1.10. A connection from the internet reaches the router and stops there unless you add a port forwarding rule to your computer.
Many mobile and some home providers go further and use carrier-grade NAT (CGNAT): several customers share one public address, and your router itself gets an address from 100.64.0.0/10. Then no rule on your side can open a port; ask the provider for a public IP or use a tunnel or VPN service.
Even with forwarding in place, the firewall on the computer (Windows Defender Firewall, ufw, firewalld) must allow the port, and the program must listen on all interfaces (0.0.0.0), not only on 127.0.0.1.
UDP cannot be checked this way: a UDP service usually stays silent to packets it does not understand, so “no answer” means nothing. This check uses TCP only.
Frequently asked questions
What is port 80 used for?
Port 80 is plain HTTP, the unencrypted web. Browsers use it when an address starts with http://; today most sites only answer on 80 to redirect visitors to HTTPS on port 443.
Is port 80 TCP or UDP?
Port 80 uses TCP. IANA reserves the number for both TCP and UDP, but in practice only TCP is used.
Is it safe to open port 80?
Traffic on port 80 can be read and changed by anyone on the path, so do not serve logins or personal data over it. Keep 80 open only to redirect to HTTPS and to pass ACME HTTP-01 challenges when issuing certificates.
How do I free port 80 if it is already in use?
Find the process: on Windows run netstat -ano | findstr :80 and stop it with taskkill /PID <pid> /F; on macOS or Linux run lsof -i :80 and stop it with kill <pid>.