Port Checker

A network port is a number (1–65535) that identifies a specific service or application on a host. When you connect to a website, your browser uses port 443 for HTTPS. When you SSH into a server, you use port 22. Ports allow multiple services to run on the same IP address. The combination of IP + port uniquely identifies a connection endpoint.

Ports are divided into three ranges: well-known (0–1023), registered (1024–49151), and dynamic (49152–65535). This tool helps you look up what common ports are used for.

Web services typically use 80 (HTTP) and 443 (HTTPS), with 8080 and 8443 as common alternatives. Email uses 25 (SMTP), 110 (POP3), 143 (IMAP), 465, 587, 993, and 995 for secure variants. Databases: 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis), 27017 (MongoDB). Remote access: 22 (SSH), 23 (Telnet), 3389 (RDP), 5900 (VNC). Development tools often use 3000, 4200, 5000, 5173, 8000, and 8080.

Port scanning probes which ports are open on a target host. It's used for network diagnostics and security audits. Browsers cannot perform port scanning because JavaScript has no raw socket access. Use nmap, netcat, or dedicated online scanners for that. This tool is purely educational — a reference for understanding what services run on which ports.