Check whether a website or host is up from outside your own network. Enter a hostname, IP address or URL, and the tool checks DNS, the TCP ports you choose, the HTTP(S) response with its redirects and the TLS certificate, from our server in the EU. Every check gets its own result and timing, so you see which layer fails, and you get the PowerShell commands to repeat the same checks from your side.
Is a host up? DNS, TCP ports, HTTP status with redirects and the TLS certificate, checked from our server in the EU.
Server lookup, rate limitedUp to 5, separated by commas. Default: 80 and 443.
| Check | Result | Time |
|---|
Requests, in order (redirects and the plain HTTP fallback)
Run these on your own machine: if our server gets through and you do not, the problem is between you and the host.
How to use
- Enter a hostname (
www.example.com), an IP address or a full URL. A URL is fine: the tool takes the host from it. - Leave Ports empty to test 80 and 443, or enter up to five ports separated by commas, for example
22, 443, 3389. - Press Check. The checks usually finish in a few seconds; a host that drops every packet takes longer, because each check waits for its timeout.
- Read the verdict first, then the table: the first failing row is usually where the problem is.
- Copy the PowerShell block and run it on your own machine to compare our view with yours. Use Share link to put the exact check in a ticket.
What each check tells you
| Check | OK means | A failure usually means |
|---|---|---|
| DNS A/AAAA | The name resolves; the addresses are listed. | No records: typo, expired domain, deleted record, or a name that exists only in internal DNS. |
| TCP port | Something accepts connections on that port. | Closed: the host answered but nothing listens, so the service is stopped. Filtered: no answer at all, usually a firewall dropping the traffic. |
| HTTP(S) | The status code, after up to five redirects. | 5xx: the web server is up but the application behind it fails. Timeout: the server accepts the connection and never answers. |
| TLS certificate | Issuer, expiry date and days left, name match, trusted chain. | Expired, issued for another name, or an incomplete or self-signed chain. Browsers show a warning even though the site is up. |
The verdict sums it up. Up from our server: every check answered. Partially reachable: some checks failed, and the summary names them. Down from our server: nothing answered. A ping reply, where our server can send one, only ever counts in the host’s favour, because many hosts block ICMP on purpose.
FAQ
The site works for me, but the check says it is down. Who is right?
Both can be. The checks run from our server in the EU, not from your network. A firewall that only allows your office, geo-blocking, a CDN that challenges automated requests, or a name that exists only in your internal DNS all give different answers from different places. Run the PowerShell block from your side: if your results match ours, the problem is on the host; if they differ, it is the path or the policy between.
Can I check ports other than 80 and 443?
Yes, up to five per check, separated by commas: 22 for SSH, 3389 for RDP, 25 or 587 for mail, 5985 for WinRM. Closed and filtered are different answers: closed means the host is there and the service is not; filtered means something in between drops the packets.
Can I check a server on my internal network?
No. Private, loopback and link-local addresses are refused, and names that resolve to them too, including after a redirect. Our server cannot reach your LAN anyway. For internal hosts, run the PowerShell commands from a machine inside the network.
Why does the tool not rely on ping?
Many servers and firewalls block ICMP on purpose, so a missing ping reply says very little. The verdict is based on DNS, TCP, HTTP and TLS, which is what users actually depend on. If you need ping and traceroute, Test-Connection and tracert from your own machine are the right tools.
Does it warn before a certificate expires?
It shows the expiry date and the days left on every check, plus the issuer and whether the certificate covers the name. It is a spot check, not monitoring: for alerts, use a monitoring system.
Are there limits, and what does the checked host see?
Each visitor can run 6 checks per minute and 100 per day. The host you check sees a connection from our server’s IP address, not yours. The hostname you enter is not stored; details are in the privacy policy.
Practical examples
Example 1: “the website is down”. DNS resolves, port 443 is open, the certificate is valid, but HTTP(S) returns 502 Bad Gateway. The network and the web server are fine; the application behind the reverse proxy is not answering. Go to the application logs, not the firewall. Run this check.
Example 2: RDP after a firewall change. Check the public name with ports 443, 3389. If 3389 comes back filtered, the new rule drops the traffic before it reaches the server; if it comes back closed, the traffic arrives and Remote Desktop is not listening. Two different fixes, one check. Run this check.
Example 3: a renewed certificate that is still old. You renewed the certificate, but the check still shows the old expiry date. The new file is on disk and the web server was not reloaded, or a load balancer or CDN in front still serves its own copy. Reload the service or update the certificate on the front end, then check again. Run this check.
Related guides and tools
Related guides
- Test-NetConnection in PowerShell: the same port and route checks from your own machine.
- tracert and pathping in Windows: find the hop where the path breaks.
- NETSTAT command in Windows: confirm on the server that the service is actually listening.
- New-NetFirewallRule: open the port on the Windows firewall and verify the rule.
- netsh command in Windows: firewall, proxy and interface settings from the command line.
- Windows Network Troubleshooting Cheat Sheet: the Windows commands for each layer of a network problem, on one printable page.
Other tools
- Port Checker: test one TCP port from outside your network
- Certificate and CSR decoder: read the certificate the TLS row reports, field by field
- DNS lookup: read every record type for the name
- DNS propagation checker: after a DNS change, see which resolvers still hold the old answer
- My IP and network info: what the internet sees of your own connection