SSL certificate checker

See when a certificate expires, who issued it and whether browsers trust it.

What is an SSL certificate?

An SSL (strictly, TLS) certificate is what lets a browser talk to a website over HTTPS: it proves the site is really the domain in the address bar and lets the connection be encrypted. Certificates are issued by certificate authorities, like Let's Encrypt, Google Trust Services, Sectigo or DigiCert, and they only last for a limited time, usually 90 days to a year.

What this checker looks at

  • Expiry. The date the certificate stops working. After that, every visitor sees a full-page security warning.
  • The name. Whether the certificate covers the exact name you checked. A certificate for www.yourbakery.com doesn't cover yourbakery.com unless both are listed.
  • The chain. Whether browsers can follow it up to an authority they trust. A missing intermediate certificate works in some browsers and fails in others, which makes it confusing to track down.
  • The issuer. Who issued it, and whether it's the kind that usually renews itself.

Common problems

  • Auto-renewal stopped. Let's Encrypt certificates renew themselves only while the renewal job keeps running and can still prove you own the domain. A server move, a firewall change or a DNS change often breaks it silently.
  • Missing intermediate certificate. Install the full chain file (often fullchain.pem or a "CA bundle") rather than the certificate alone.
  • Wrong name. Add every name visitors use, including the www. version, when you issue the certificate.

We check from our own servers on port 443, the way a browser would. Pingerer can watch a certificate for you and warn you 30, 14 and 3 days before it expires.

More free tools

  • Full check: Free, instant, no sign-up. See what's wrong in plain English.
  • DNS lookup: Every record for a domain, with what each one does.
  • DMARC & SPF: Find out if your email can be spoofed or sent to spam, and get the exact record to fix it.
  • Is it down?: We'll check the site right now from our servers, not your network.
  • Domain expiry: When a domain expires and where it's registered, straight from the registry.