Open Port Checker
Check whether TCP ports are open on any host with real connection probes from our server. Common and custom ports. Free.
Check open ports
Enter a host and select ports to test. We attempt a real TCP connection to each.
What this open port checker does
Common use cases
- 1Verifying a service is reachable
- 2Checking a firewall rule
- 3Confirming a web or DB port is open
- 4Diagnosing a connection issue
- 5Auditing exposed ports
- 6Testing after a config change
Related tools
About port checking
A port check attempts a TCP connection to a specific port on a host. If the connection is accepted, a service is listening and the port is open; if it is refused or times out, it is closed or filtered by a firewall.
This tool probes from our server, so it shows what the outside internet can reach — which may differ from inside your own network. It only opens and closes the connection (it sends no payload), and results are honest: a firewall that silently drops packets appears the same as a closed port.
More Free Tools Where This Came From
This utility is one of dozens of free, no-login tools for DNS, email, SEO and developers — all instant and private.
HostCloud.in · Pune, India · Serving 34,987+ Websites Since 2020
Got Questions? We Have Answers.
How does it check a port?
It attempts a real TCP connection to each port from our server. If the connection is accepted the port is open; if refused or timed out it is closed or filtered.
Why does a port show as closed when I know it's open?
The check runs from our server, not your network. A firewall may allow you but block us, or filter our IP. Results reflect what the public internet can reach.
Why is port 25 always closed?
Our host (Cloudflare) blocks outbound port 25 to prevent spam, so SMTP checks on port 25 may read as closed even when the server accepts mail.
Does it send any data?
No. It only opens and closes the TCP connection — no payload is transmitted.