Free Port Checker Tool Online

Check if ports are open free online. Test connectivity, detect open ports. Instant results, browser-based, no registration, network diagnostics.

Free Port Checker Tool Online

Check if a TCP port is open on any host with common port presets

Quick Port Diagnostics

Test port connectivity with common presets

Any Port Number

Check any TCP port from 1 to 65535 on any hostname or IP address.

Common Port Presets

Quick-select buttons for common web ports (80, 443), email ports (25, 587, 993), and other popular service ports.

Instant Results

Get immediate feedback on whether a port is open and accepting connections or closed and unreachable.

About This Tool

A port checker tests whether a specific network port on a host is open and reachable from the internet. Ports are numbered endpoints that identify services on a machine: port 80 for web traffic, 443 for secure web, 22 for SSH, and so on, so a service is reachable only if its port accepts connections.

This is a common step in diagnosing why a server or game host is not reachable: the service might be down, a firewall might be blocking the port, or a router might not be forwarding it. The checker attempts a connection from outside your network, which tells you what an external client would experience rather than what works locally.

A closed result can mean several things: the service may be down, a firewall may be dropping the connection, or a router may not be forwarding the port to the right machine. Because the check comes from outside your network, it reflects what an external client sees, which is exactly what matters for reachability.

How to Use It

  1. Enter the host address and the port number to test.
  2. Run the check.
  3. See whether the port is open (reachable) or closed or filtered.

References

  1. Service Name and Transport Protocol Port Number Registry - IANA
  2. RFC 6335: IANA Procedures for Port Number and Service Name Management - IETF
  3. List of TCP and UDP port numbers - Wikipedia