Can this confirm a port is closed?

Not reliably. Browsers can only attempt HTTP-style connections, so a non-HTTP service or strict firewall can look the same as a closed port.

How do I check whether a port is open?

Enter a host you are authorized to test, choose a port, and run the browser-safe connection attempt. Treat the result as an initial signal, not a protocol-level scan.

Which ports are commonly checked?

Web services commonly use 80 and 443; SSH often uses 22, FTP 21, SMTP 25, and Remote Desktop 3389. Service configuration may differ.

Internet & NetworkReady to use

Port Checker

Check whether a given host and port appear reachable from the browser environment.

Guide

Interactive workspace

No account required

Port Checker

Check common ports at once

Test HTTP, HTTPS, SSH, FTP, SMTP, and MySQL default ports on this host in one click.

How to use it

Enter a hostname or public IP address you are authorized to test.
Choose the port or a common-port preset.
Run the browser-safe connection attempt and read the result with its caveat.
If a port appears unreachable, confirm it with a protocol-specific client or server logs.

What is Port Checker?

Check whether a given host and port appear reachable from the browser environment.

How it works

SiteIndex attempts a browser HTTP connection to the given host and port. The Advanced panel checks common ports (HTTP, HTTPS, SSH, FTP, SMTP, MySQL) on the same host in one click.

Common uses

Check whether a specific port responds before troubleshooting further.
Scan common service ports on a host you manage.
Confirm a web server is reachable on 80/443 after a firewall change.

Limitations

Results depend on the browser, network, input, and external service involved.
This tool is informational and does not replace specialist diagnostics or professional advice.

Frequently asked questions

Can this confirm a port is closed?: Not reliably. Browsers can only attempt HTTP-style connections, so a non-HTTP service or strict firewall can look the same as a closed port.
How do I check whether a port is open?: Enter a host you are authorized to test, choose a port, and run the browser-safe connection attempt. Treat the result as an initial signal, not a protocol-level scan.
Which ports are commonly checked?: Web services commonly use 80 and 443; SSH often uses 22, FTP 21, SMTP 25, and Remote Desktop 3389. Service configuration may differ.

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