Is a website down, or is it just you?

The short answer: check the site from somewhere other than your own connection. If it loads for an outside checker but not for you, the problem is almost always on your side: your connection, your DNS cache, your browser, an extension or a firewall. If the checker can't reach it either, or gets an error code such as 500 or 503, the problem is probably the website itself, and the status code tells you roughly where to look.

When a website won't load, it is hard to know whether to fix something at your end or wait for the site's owners. This guide shows a quick way to tell the difference, explains what the common error codes mean, and lists the fixes worth trying on your own device first.

Start by checking from somewhere else

Your browser only tells you what happened on your own connection. To find out whether a site is down for everyone, you need a second opinion from a different network. The Website Down Checker does this: it asks our server to connect to the site, and shows you what came back.

The result has two parts. The headline tells you whether the server answered and with what status code. The details underneath show how long each stage took, which IP addresses the name points to, whether the site redirected, and whether it ended up on HTTPS.

If the site works for us but not for you

This is the most common outcome. The site is up, but something between you and it is getting in the way. Work through these in order, because the early ones are quickest.

• Try another device or network. Load the site on your phone using mobile data rather than Wi-Fi. If it works there, the problem is your home or office network, not your computer.
• Try a private window. A private or incognito window starts without your cookies and usually without extensions. If the site works there, clear the site's cookies or switch off extensions one at a time. Ad blockers and privacy extensions are frequent culprits.
• Check the exact address. A typing mistake, an old bookmark or a missing www can send you to an address that no longer exists.
• Restart the router. It sounds too simple, but it clears stale connections and often the router's own DNS cache.
• Look at security software. A firewall, antivirus web filter, parental controls or a work network's filter may block particular sites. A VPN can also cause this, because some sites block traffic from VPN addresses.

Clear your DNS cache

Your computer remembers the IP address of each website for a while, so it doesn't have to look it up every time. If a site has recently moved to a new server, your computer may still be trying the old address. Clearing the cache makes it look the name up again.

On Windows, open Command Prompt and run the command below. Microsoft's ipconfig documentation describes /flushdns as clearing and resetting the DNS client resolver cache.

ipconfig /flushdns

On a Mac, the equivalent in Terminal is shown below. It asks for your password.

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

Browsers keep their own short-lived cache too, so close and reopen the browser after clearing the system cache. Your router and your internet provider's DNS servers also cache answers, and you can't clear those yourself. They expire on their own after a set time, called the TTL.

To check what the name should point to now, run a DNS Lookup on the domain and compare the A and AAAA records with the IP addresses the Website Down Checker connected to. If they match, DNS is not the problem.

If the site is down or showing an error for us

When our server can't reach the site either, the problem is very likely at the website's end. The result tells you which stage failed, which narrows things down.

• The name doesn't resolve. No IP address could be found for the domain. The domain may have expired, its DNS records may have been deleted, or its DNS provider may be having trouble. A DNS Lookup will show whether any records exist.
• The connection times out or is refused. The address exists, but nothing answered. The server may be switched off, overloaded or behind a firewall that drops outside connections.
• The certificate check fails. The server answered, but its HTTPS certificate is expired, issued for a different name or not trusted. Browsers show a full-page warning in this case. The SSL Certificate Checker shows exactly what is wrong.
• The server answers with an error code. The server is running, but the page itself failed. We show this as Attention rather than Online, because a 404 or 503 page is not the site working.

What the error codes mean

Every web response carries a three-digit status code. Codes starting with 2 mean success, 3 means a redirect, 4 means the request had a problem, and 5 means the server had a problem. MDN's list of HTTP status codes explains all of them. These are the ones you are most likely to see when a site seems down.

Cloudflare's 52x errors

Many sites sit behind Cloudflare, which adds its own codes when it can't reach the site's real server. According to Cloudflare's 5xx error documentation, 521 means the web server refused the connection, 522 means the connection timed out, 523 means the origin could not be reached, 524 means the server took too long to respond, 525 means the HTTPS handshake failed, and 526 means the server's certificate is invalid. In every case Cloudflare itself is working; the site's own server is the problem.

If you run the site

If the site is yours, a quick health check saves guesswork. Work from the outside in.

1. Run a DNS Lookup and check the A and AAAA records point to your current server. If you recently moved hosts, old addresses are a common cause of "down for some people".
2. Run the SSL Certificate Checker. An expired certificate makes the whole site look broken to visitors.
3. Look at the status code and response time in the Website Down Checker. A slow first byte with a 200 usually means the server or database is struggling.
4. Check your hosting control panel for an outage notice, and look at the server's error log for the time of the failure.

The Website Health Check runs several of these checks together and summarises them on one page, which is useful after a change or when you aren't sure where to start.

Common questions

The checker says the site is online, but it shows a blank page for me. Why?

Our check confirms the server answered. It doesn't run the page's scripts, so a site that depends on JavaScript can still fail in your browser. Try a private window without extensions, or another browser.

Why does the site work on my phone but not my laptop?

The phone is probably on a different network, or has a fresh DNS cache. Clear the DNS cache on the laptop, restart the browser and check for extensions or security software blocking the site.

Can a site be down in one country and up in another?

Yes. Large sites use servers in many places, and an outage can affect one region. Some sites also block visitors from certain countries. Our check runs from one location, so it can't rule out a regional problem.

How long should I wait before trying again?

For a 503 or a 52x error, a few minutes is usually enough for a brief problem. If a site has just moved to a new server, your provider's DNS may take up to a few hours to catch up.

Does checking a site tell the owner?

Our server makes one ordinary request, similar to a visitor loading the home page. It shows up in their logs as a request from our server, not from you.