Why keep an eye on your certificate?
The SSL (strictly speaking, TLS) certificate is what lets your site run on HTTPS: traffic between the browser and the server is encrypted, and visitors know they are talking to the right site. Without a valid certificate, browsers show a “Your connection is not private” warning that drives most visitors away, and contact or payment forms stop working. HTTPS is also a signal used by Google.
Certificates have a limited lifetime: usually 90 days for free Let’s Encrypt certificates, and at most 200 days for any certificate issued since 15 March 2026 (a CA/Browser Forum rule that will shorten lifetimes further in the coming years). An automatic renewal that silently fails is enough to take a site offline overnight.
What the checker looks at
- The expiry date and the number of days left: orange under 30 days, red under 15.
- The domain covered: the certificate must match the address exactly, with or without “www” depending on the names it contains.
- The chain of trust: the certificate must be issued by an authority trusted by browsers and served with its intermediate certificates.
- The issuer, the start of validity and the protocol (TLS 1.2 or 1.3 recommended).
If something is wrong
If the certificate expires soon, check that automatic renewal is enabled in your hosting panel, or ask your host. If the name does not match, you need a certificate that also covers the variant your visitors use, such as example.com and www.example.com. If the chain is not trusted, the intermediate certificate is often missing from the server configuration. Once the certificate is fixed, make sure every HTTP address redirects to HTTPS in a single step with the redirect checker.
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Frequently asked questions
How long is an SSL certificate valid?
Since 15 March 2026, at most 200 days for a public certificate, and this will drop further in the coming years. Let’s Encrypt certificates usually last 90 days.
What happens when the certificate expires?
Browsers show a security warning and most visitors leave. Forms and payments stop working properly.
Does the checker access my site’s content?
No. It only opens a secure connection to read the certificate, then sends a HEAD request to check that browsers trust it.