What does "open" mean?

An open port means a service (like a web server, SSH daemon, or database) is actively listening on that port and accepting TCP connections. This is expected for services you are running intentionally.

What does "closed" mean?

A closed port means the host is reachable but no service is listening on that specific port. The host responds with a TCP RST (reset) packet.

What does "filtered" mean?

A filtered port means a firewall or security device is silently dropping the connection attempt. You get no response (timeout). This is the most common state for ports blocked by cloud firewalls (AWS Security Groups, Cloudflare, etc.).

Can I check UDP ports?

This tool checks TCP ports only. UDP port checking is unreliable over the internet because UDP is connectionless -- there is no handshake to confirm the port is open. For UDP, use nmap with the -sU flag from a command line.

Is my IP address logged?

The port check is performed by our server, so the target host sees our server IP, not yours. We do not permanently log check requests.

Why does the check fail?

Common reasons: (1) The host does not exist or is unreachable. (2) DNS resolution fails. (3) Your network blocks outbound connections. (4) The backend API endpoint is not yet configured. In all cases, the tool provides command-line alternatives.

What port should my web server use?

Standard web servers use port 80 (HTTP) and 443 (HTTPS). Port 8080 is commonly used for development servers or proxies. Always run production sites on port 443 with TLS.

Can I scan multiple ports at once?

This tool checks one port per request. For multi-port scanning, use nmap from the command line (nmap -p 1-1000 example.com). Mass port scanning without permission may violate terms of service or laws.

Security & Network

Open Port Checker

Check if a specific port is open on any host. Tests TCP connectivity with timeout detection. Useful for debugging firewalls, servers, and network configurations.

100% free
No sign-up
No limits
Instant results

Host (domain or IP)

Port

Common ports

What this tool does

Check any port (1-65535) on any host
Common port presets: HTTP, HTTPS, SSH, FTP, MySQL, PostgreSQL
Timeout detection for filtered ports
Connection latency measurement
Check history (last 20 checks)
Command-line alternatives provided

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The short version

What is Open Port Checker?

An open port checker tests whether a specific TCP port is reachable on a remote host.

When a port is open, a service is listening and accepting connections. When it is closed, no service is listening. When it is filtered, a firewall is blocking the connection. This tool sends a check request to our backend API which attempts a TCP connection to the specified host and port, returning the result with latency information.

Step by step

How to use Open Port Checker

1
Enter the host
Type the domain name (example.com) or IP address (192.168.1.1) of the server you want to check. Do not include the protocol (http://).
2
Set the port
Enter the port number (1-65535) or click one of the common port presets: 80 (HTTP), 443 (HTTPS), 22 (SSH), 3306 (MySQL), etc.
3
Click Check Port
The tool sends a TCP connection test to the specified host and port. Results appear within a few seconds, including latency if the port is reachable.
4
Review the result
Open (green) means a service is listening. Closed (red) means no service is responding. If the check fails, command-line alternatives are shown for manual testing.

What's inside

Everything this tool
does for you

Check any TCP port (1-65535) on any host or IP address
12 common port presets with service names (HTTP, SSH, MySQL, etc.)
Connection latency measurement in milliseconds
Timeout detection for filtered/firewalled ports
Check history showing the last 20 results
Color-coded status: green (open), red (closed), yellow (error)
Command-line alternatives provided when API is unavailable
No software installation required -- works in your browser

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Questions

Frequently asked questions

This tool fixed one thing.
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What is Open Port Checker?

How to use Open Port Checker

Enter the host

Set the port

Click Check Port

Review the result

Everything this tooldoes for you

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Frequently asked questions

What does "open" mean?

What does "closed" mean?

What does "filtered" mean?

Can I check UDP ports?

Is my IP address logged?

Why does the check fail?

What port should my web server use?

Can I scan multiple ports at once?

This tool fixed one thing.Now fix the whole site.

Everything this tool
does for you

This tool fixed one thing.
Now fix the whole site.