SSL certificate checks

An SSL certificate is what lets a site run over HTTPS, showing visitors the connection is secure. If it expires, the site stops being reachable securely even when every line of code behind it works perfectly. It's a mistake that always starts the same way: someone had it on their calendar years ago, then the calendar changed, and the expiry date just sat there, waiting for the worst moment to make itself known.

How it works

Every time the monitor checks the site, it also checks the certificate's expiry date, its issuer and the validity of the whole chain, the set of intermediate certificates linking the site's own certificate to an authority browsers recognize. There's nothing to configure beyond the site's address: if it runs on HTTPS, the check starts on its own. Renew the certificate and the count resets, so you don't end up with reminders for something you've already fixed.

Why it's easy to forget

The certificate on a personal site was often set up by whoever built it, years ago, and nobody's touched it since. If it expires during a busy stretch, the browser flags the site as unsafe right as a visitor was about to get in touch, and that contact is lost without you ever knowing.

With several sites to track, each with a certificate renewing in a different month and sometimes through a different provider, keeping them all straight on a shared calendar works until someone goes on holiday or changes jobs. With automatic warnings, that responsibility stops depending on one person's memory.

Nothing to set up

Unlike other checks, there's nothing to configure with the team here: if the site is already monitored over HTTPS, the certificate check is already on. If you still need to set up HTTP monitoring for the site, that's the part worth deciding together.