What's the difference between TCP and UDP ports?

TCP (Transmission Control Protocol) provides reliable, connection-oriented communication. UDP (User Datagram Protocol) provides fast, connectionless communication. The same port number can be used by both TCP and UDP.

How can I check open ports on my computer?

On Windows, use the 'netstat -an' command. On macOS/Linux, use 'netstat -an' or 'ss -tuln' to view listening ports.

Free Common Port Reference

Search and browse TCP/UDP well-known port numbers, service names, and protocol information · Pure frontend · Data stays local

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Common Port Reference - TCP/UDP Well-Known Ports

This free online tool provides a quick reference for well-known TCP and UDP ports (0-1023). Perfect for network engineers, system administrators, and developers who need to look up port information.

Features

Search by port number or service name
Filter by TCP, UDP, or both protocols
Real-time filtering and count
Detailed port descriptions
Pure client-side processing

Use Cases

Configuring firewall rules
Troubleshooting network services
Learning network protocols and ports
Security audit and port scan analysis
Server and network device configuration

FAQ

What are well-known ports?

Well-known ports (0-1023) are assigned by IANA for standard network services. They typically require administrative privileges to use.

What's the difference between TCP and UDP?

TCP provides reliable, connection-oriented communication. UDP provides fast, connectionless communication. Many services support both protocols.

What are Registered and Dynamic ports?

Registered ports (1024-49151) are registered by IANA for specific services. Dynamic/Private ports (49152-65535) are for temporary use.

🔌 Common Port Reference