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About this tool
Search well-known and registered TCP/UDP ports by number, service name or protocol, with IANA range classification.
This explorer looks up TCP and UDP port numbers by number, service name or keyword, and classifies any port into the IANA ranges defined by RFC 6335 — well-known (0-1023), registered (1024-49151) and dynamic (49152-65535). It is built for developers, sysadmins and network engineers who need to identify what runs on a port, pick a safe port for a new service, or write a firewall rule without guessing.
Open Port Number Reference Explorer on AltFTool — it loads instantly in your browser.
Paste your code or data sample into the workspace.
Pick the format, conversion, or analysis you need.
Copy the polished result straight back into your project.
Type a number to get the service, or a service name to get its port.
Every numeric lookup states whether the port is well-known, registered or dynamic.
Each entry says whether the assignment is official or a widely used product default.
RFC 6335 splits the 0-65535 port space into three ranges: 0-1023 are system or well-known ports managed by IANA, 1024-49151 are user or registered ports that anyone can register, and 49152-65535 are dynamic or private ports that are never assigned and are used for ephemeral client connections.
On Unix-like systems, binding a listener to a port from 0 to 1023 traditionally requires root privileges (or the CAP_NET_BIND_SERVICE capability on Linux) because these well-known ports carry trusted services like SSH on 22 and HTTPS on 443, and the restriction stops unprivileged users from impersonating them.
Port 80 carries plain unencrypted HTTP, while port 443 carries HTTP over TLS (HTTPS); on UDP, port 443 also carries HTTP/3 over QUIC. Modern browsers default to 443 and most sites redirect port-80 requests straight to it.
Yes, as long as they differ in transport protocol or IP address — TCP 53 and UDP 53 are separate sockets, and two processes can each bind port 8080 on different interfaces. Two listeners cannot bind the same protocol, address and port at once, which is the familiar 'address already in use' error.