Five checks, one clear answer
The checker runs the same troubleshooting steps a server administrator would, in the same order, then tells you in plain English which one broke and what to do about it.
Domain Registration
Looks the domain up at the official registry (over RDAP, the modern replacement for WHOIS) to confirm it's registered, who the registrar is, and how many days remain before it expires. An expired domain stops resolving completely, so this is checked first. If you enter a subdomain, the parent domain is looked up automatically.
DNS Resolution
Finds your domain's nameservers, asks them directly for the authoritative answer, then compares that against Google (8.8.8.8), Cloudflare (1.1.1.1) and Quad9 (9.9.9.9) to see whether the change has reached the wider internet. Also lists every DNS record — A, AAAA, CNAME, MX, NS, TXT, SOA and CAA — so you can spot a missing or wrong record at a glance.
SSL Certificate
Opens a real TLS connection and inspects the certificate: expiry date, which hostnames it covers, the issuing authority, TLS version and cipher. It distinguishes between an expired certificate, a hostname mismatch, a self-signed certificate and an incomplete chain — four very different problems that browsers report with the same vague warning.
Server Response
Requests the site over HTTPS (falling back to HTTP), follows the full redirect chain hop by hop, and reports the final status code, response time, web server software and whether a CDN such as Cloudflare sits in front. Also reports which security headers — HSTS, CSP, X-Frame-Options and others — the server is sending.
Email & Anti-Spoofing
Checks the DNS side of your email: MX records that receive mail, the SPF record that says who may send as you, the DMARC policy that stops spoofing, and DKIM signing keys across common selectors. Reported separately from site availability, because a website can be perfectly online while its email quietly lands in spam.
Website down — common questions
Still stuck after the checker runs? A server engineer can dig into the underlying cause.
This is almost always DNS propagation — different internet providers and DNS resolvers can briefly show different results after a DNS change. The checker above queries Google, Cloudflare and Quad9 directly and shows you if they disagree.
A 502 means the web server (or a proxy like Cloudflare or Nginx in front of it) received an invalid response from the application server behind it — often a crashed backend process, a timeout, or a misconfigured reverse proxy.
503 means the server is reachable but currently unable to handle the request, usually because it's overloaded, under maintenance, or a service like PHP-FPM or a database has stopped responding.
Run this checker — it queries multiple public DNS resolvers (Google, Cloudflare, Quad9) directly and shows you the IP address each one currently returns for your domain, side by side.
This usually means the SSL certificate has expired, doesn't match the domain name, or isn't trusted by browsers. The checker inspects the certificate directly and tells you which of these applies. See our SSL installation service if you need it fixed.
Yes, the Website Down Checker is completely free with no signup required. There's a small rate limit per visitor to keep the service fast for everyone.
Found a problem the checker can't fix for you?
Our engineers can jump in and fix DNS, SSL or server issues directly — 24/7, no long-term contract required.