NetCheck Tools

Check SSL Certificate Expiration

Find out exactly when a domain's SSL certificate expires and how many days remain — before your visitors find out the hard way.

Why expiration monitoring matters

Certificate expiry is the most preventable outage on the internet, yet it still takes down major sites every year. The typical failure story is always the same: the person who set up the certificate left, the renewal email went to a dead mailbox, and the first alert was customers reporting security warnings.

A sane renewal policy

  • Automate: use ACME (Let's Encrypt, ZeroSSL or your CA's ACME endpoint) so certificates renew unattended
  • Alert early: treat 30 days remaining as a warning and 14 days as an incident — automation should have renewed by then
  • Check every endpoint: apex, www, API and mail hostnames often carry separate certificates with separate clocks

While you're at it, run the full SSL certificate installation check — expiration is only one of the ways certificates fail.

Frequently asked questions

›How do I check when my SSL certificate expires?

Enter your domain above. The result shows the certificate's exact “valid to” date and the number of days remaining. Anything under 30 days is highlighted so you can renew in time.

›What happens when an SSL certificate expires?

Browsers show a full-page security warning that most visitors will not bypass, API and mobile clients start failing with TLS errors, and automated integrations break. Traffic and revenue drop immediately — expiration is effectively an outage.

›How long are SSL certificates valid?

Publicly trusted certificates are capped at 398 days, and the industry is moving shorter: Let's Encrypt issues 90-day certificates, and maximum lifetimes are scheduled to shrink further in the coming years. Automated renewal is the only sustainable strategy.

›Why does my renewed certificate still show the old date?

The new certificate is on disk but the server hasn't reloaded it, or another layer (load balancer, CDN, second server in the pool) still serves the old one. Reload the service and re-run this check against each entry point.

Related tools

SSL Checker

Full certificate details: issuer, SAN, fingerprints.

SSL Certificate Checker

Verify the whole installation, not just the date.

Check If a Port Is Open

Confirm the server is reachable on port 443.