What is a port scanner?

A port scanner checks which TCP or UDP ports are open on a host. Open ports indicate active services — for example port 80 for HTTP, 443 for HTTPS, and 22 for SSH.

Can I scan any IP address?

You can scan hosts you own or have permission to test. Scanning third-party systems without permission may be illegal in your jurisdiction.

What ports does this tool scan?

You can specify individual ports or ranges. Common ports like 80, 443, 22, 21, 25, 3306, and 8080 are included as presets.

Port Scanner Online — Check Open TCP Ports Free

Scan a hostname or IP address for open TCP ports. Check which ports are open, closed, or filtered. Useful for network diagnostics and firewall verification. Free, no signup.

Notes

—Only scan hosts you own or have explicit written permission to test.
—Open = TCP connect succeeded. Closed = port refused. Filtered = timed out or blocked by firewall.
—Server enforces rate limits and an allow-list policy for permitted IP ranges.
—Scanning hosts without permission may be illegal in your jurisdiction.

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