Port Scanner - Free Online, No Signup

Host / IP Address

Browser-based port scanning is limited by CORS policies. Results may not be fully accurate. Use a dedicated tool like nmap for real network scanning.

How do you check if a port is open?

A browser-based port check sends a request to 14 common ports on a host, including 21, 22, 80, 443, 3306, 5432, 6379, and 27017, and marks each open, closed, or filtered depending on whether it answers within two seconds. Because browsers enforce CORS, results are only indicative; use nmap for a reliable network scan.

Why is a browser port scanner unreliable?

A browser cannot open raw TCP sockets, so it can only send HTTP requests and read whether they fail or time out. Cross-origin security rules hide the real response, meaning a port may look open because something answered or filtered because it was slow. A proper scanner such as nmap talks to the port directly.

Sends data to a third party. Your browser attempts connections directly to the host you enter, so that host sees the requests. Nothing is sent to The Tools Kit.

Why use Port Scanner?

Port Scanner probes a single host against a built-in list of 14 well-known ports. When you enter a hostname or IP and press Scan, the tool fires a browser fetch at each port at the same time, waits up to 2 seconds for each, and then labels every port open, filtered, or closed. The ports covered are the ones most people actually care about: FTP, SSH, Telnet, SMTP, DNS, HTTP, POP3, IMAP, HTTPS, MySQL, PostgreSQL, Redis, HTTP Alt, and MongoDB, each shown with its service name beside the number so the list stays easy to read. Everything happens client-side. No API call to our servers performs the scan and nothing about the target is stored on our end, which also means the results are bounded by what a browser is allowed to do. Cross-origin and CORS restrictions can cause a port that is genuinely open to come back as filtered or closed, so the interface includes a visible warning that browser-based scanning is limited and points you to nmap for accurate network scanning. Treat this as a fast, zero-install first look, not a security audit. You should only scan hosts you own or have explicit permission to test, and because the probe runs in your browser, the host you type stays on your machine. The workflow is deliberately minimal: one Host / IP Address field, one Scan button that also fires on Enter, and a color-coded results list. Open ports show in green, filtered in yellow, and closed in grey. There is no port range box, no custom port entry, and no multi-host batching, so if you need any of those you will move on to a dedicated command-line scanner after this quick pass.

Key benefits

Covers 14 common service ports in one click, including FTP, SSH, Telnet, SMTP, DNS, HTTP, POP3, IMAP, HTTPS, MySQL, PostgreSQL, Redis, HTTP Alt, and MongoDB.
Each port is labeled with its service name, so you see SSH or MySQL rather than just a number.
All 14 checks fire in parallel with a 2-second timeout each, so the scan finishes quickly.
The probe runs client-side with no account and no install, and nothing about the target reaches our servers.
Color-coded open, filtered, and closed statuses let you read the whole list at a glance.

Features

Scans a fixed set of 14 well-known ports rather than an arbitrary range you specify.
Accepts either a hostname (example.com) or an IP address (192.168.1.1) as the target.
Reports three states per port: open, filtered, or closed, based on how the browser request resolves.
Uses a 2-second per-port timeout via AbortController and a no-cors fetch to probe each port.
Displays a built-in notice that browser-based scanning is limited by CORS and recommends nmap for real network scanning.

Popular use cases

Sanity-check whether a web or database port such as 443 or 3306 appears reachable on your own server before digging deeper with a full tool.
Confirm at a glance which common services on a host you administer are responding versus timing out.
Teach or demonstrate the idea of open, filtered, and closed ports without installing command-line scanners.
Run a fast first pass on a host you control, then switch to nmap for an accurate, authoritative scan.

How to use Port Scanner

1
Enter a host or IP
Type a hostname or IP into the Host / IP Address field, for example example.com or 192.168.1.1.
2
Start the scan
Click the Scan button, or press Enter in the input. The button switches to Scanning while all 14 ports are checked at once.
3
Read the results
Each port appears with its service name and a status of open (green), filtered (yellow), or closed (grey) so you can spot which services responded.
4
Weigh the results against the CORS warning
Read the built-in notice above the results reminding you that browser CORS rules limit accuracy. Treat the list as a quick first pass and confirm anything important with a dedicated tool like nmap.

How do you check if a port is open?

Why is a browser port scanner unreliable?

Related tools