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Is It Down? Check If a Website Is Down Right Now

Find out whether a site is down for everyone or just for you, and which step fails.

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About Is It Down?

When a site won't open, the first question is whether it is down or the problem is your own connection. This checker tries the site from our server, one step at a time. It looks up the IPv4 and IPv6 addresses through public DNS, opens a TCP connection to the port, trying the other of 80 and 443 if that fails, completes the TLS handshake and checks the certificate, then reads the HTTP answer.

The verdict is up, answering with an error, or down, along with the step where it broke: a name that doesn't resolve, a server that won't accept connections, a failed handshake or a 5xx error. If the site is up from here but not for you, look at your own network, DNS cache, proxy or firewall. If it's down here too, the failing step tells the owner where to start. Dig deeper with the SSL Certificate Checker or DNS Lookup.

How to use Is It Down?

  1. 1
    Enter the address

    Type the domain or the full URL that won't open.

  2. 2
    Click Check

    Our server tests DNS, the connection, TLS and HTTP in order.

  3. 3
    Read each step

    Every step shows OK, a warning or a failure, with the details.

  4. 4
    Act on the verdict

    Up here but not for you points to a local problem, while down here means the site needs fixing.

Why use Cubfile for this

  • Four-step diagnosis

    DNS lookup, TCP connection, TLS handshake and HTTP answer, in order.

  • Both web ports

    If the usual port doesn't connect, the other of 80 and 443 is tried.

  • Certificate trust

    A handshake that works with an untrusted certificate shows as a warning.

  • IPv4 and IPv6

    A and AAAA records are both looked up before connecting.

FAQ

Is It Down?: questions and answers

Is the site down for everyone or just me?
If this checker says it's up, the site answers our server, so the problem is probably on your side, such as your network, DNS cache, proxy, firewall or a browser extension. If it's down here too, it's likely down more widely, though one location can't speak for every region.
What if the domain name doesn't resolve?
DNS has no address for the domain. Check the spelling, whether the domain has expired and whether its DNS records are still there. A brand-new record can take a few minutes to appear.
The site answers with an error. Is it down?
A 4xx answer such as 403 or 404 means the server is running but refused the request or couldn't find the page, so the verdict is that it answers with an error. A 5xx answer means the server itself has a problem, which counts as down. Other pages on the site can be checked in one go by pasting their addresses into the HTTP Status Code Checker.
Can it check a site on my office network?
No. We only visit public internet addresses, so private IPs and intranet names can't be reached from our server.
Is the down checker free?
Yes, with no sign-up and no daily tasks used. Each check runs live when you click and nothing is stored.
Share Is It Down? with a friendIt runs in any browser, and they can try it without signing up.

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