How to use this check
Enter a public hostname and choose one of the allowed ports to test limited TCP reachability.
NetProbe resolves public A/AAAA answers first, tests only ports 80, 443, 587 and 993, and limits checked addresses.
Choose an amount before the secure payment page opens.
Reachability probes
ReadyPort Checker
Test a small allowlisted set of public ports with anti-abuse boundaries.
Port Checker
Enter a public hostname and choose one of the allowed ports to test limited TCP reachability.
Result
Run a point-in-time diagnostic from this page. Results appear above the guide, and methodology, privacy notes and limits stay below the tool.
Optional account features
Need monitoring, history or API access?
The free check answers the immediate question on this page. Larger features can add saved history, alerts, reports, API access and regional monitoring when they are enabled for your account.
Guide and interpretation
How to interpret the result
Open means a TCP connection succeeded from the runtime; closed or timeout can reflect firewalls, service state or network path.
Example
If 443 is open but 80 times out, HTTPS may work while plain HTTP is intentionally blocked.
Common issues and next steps
A private DNS answer, unsupported port or firewall rule can block the check before any TCP connection is attempted.
Confirm the public DNS answer, test an allowed service port and review firewall or load balancer rules.
Methodology and limits
This is not a port scanner; broad ranges, private targets and arbitrary ports are intentionally unsupported.
FAQ
Why are only a few ports available?
The allowlist reduces abuse risk and keeps the free tool focused on common web and mail service diagnostics.
Does “closed” mean my server is down?
Not always. It may mean the service is not listening, a firewall blocks the runtime or the chosen port is not meant to be public.
Support the free diagnostics
Keep the free checks useful by sharing corrections and using the practical pages first. No payment provider is connected here.