How do I check if a port is open?

Enter the public host and TCP port above, then run the check. Open means our probe completed a TCP handshake; closed or timeout usually means a firewall or idle service.

What is an open network port?

An open port accepts TCP (or UDP) connections for a listening service. On the public internet that often means a web, mail, or remote-admin service is reachable.

How do I test TCP ports?

Use this port checker, or tools such as Test-NetConnection and nc, against a host you are authorised to probe. Always respect ownership and policy.

Why is a port closed?

Nothing may be listening, or a firewall may reject the connection (ECONNREFUSED or filtered timeout). Check local listeners, security groups, and ACL order.

Which ports are commonly used by web servers?

HTTP commonly uses TCP 80 and HTTPS uses TCP 443. Alternate web ports such as 8080 or 8443 appear on labs and reverse proxies.

What is Port Checker?

A free online tool that tests TCP reachability of a port on a public host for students and network administrators.

How does the Port Checker work?

After validating the target is public, our server opens a short TCP connection and reports open, closed, timeout, or error with latency.

How do I use the Port Checker?

Type a host, pick a port chip or custom port, then tap Check port. Try presets such as github.com:22 for practice.

Is this Port Checker free to use?

Yes. It is free with rate limits to keep the service fair for everyone.

Can I use the Port Checker on mobile?

Yes. The page works on mobile browsers for quick remote checks.

Free Port Checker Online, Test Open TCP Ports

Free Port Checker Online, Test Open TCP Ports | Binary Tech