HTTPS certificate monitoring & expiry reminders
Every check of an HTTPS site also validates the certificate: validity window, Domain match, and chain completeness. Certificate state shows on the site detail page; remaining days change color by tier.
#Expiry reminders
- By default, reminders go out in stages before expiry (e.g. one email each at 30 / 7 / 3 / 1 days); customize them under System settings in the SSL reminder stages section.
- Expired and not replaced: an incident is declared and alerts fire.
- Reminders are sent once per stage per site — no per-check bombardment.
#Common questions
The certificate looks fine but I get SSL errors?
Browser and curl trust stores can differ: with an incomplete chain (missing intermediate certificate) browsers can fill the gap automatically, curl can't. The site detail page has a TLS diagnostic entry that shows the exact stage.
Multiple servers / CDN — certificates differ
You can pin the site to specific check nodes and verify the certificate from different vantage points; the multi-region speed test works for a quick comparison too.
If all sites at once report SSL errors, the platform's own CA root bundle is usually out of date — unrelated to your site. Contact the platform to update cacert.pem.
Related: Certificate shown differently than the browser · Site detail page