Source: https://uptimeify.io/resources/platform-and-support/glossary/ssl-expiry

# SSL Expiry

> SSL expiry is the date an SSL/TLS certificate stops being valid, after which browsers reject the connection.

Every [TLS certificate](/resources/platform-and-support/glossary/ssl-certificate) has a fixed validity period. Once it expires, every visitor sees a full-page security warning, a complete, self-inflicted outage that is entirely preventable.

Expiry monitoring checks the remaining validity and warns days in advance, giving you time to renew before users are affected. It is one of the highest-value, lowest-effort checks you can run.