SSL Certificate Checker
Check a domain’s SSL/TLS certificate — issuer, validity dates, and days until expiry.
About this tool
An expired or misconfigured certificate breaks HTTPS and scares away visitors. Inspect any site’s certificate, including who issued it and when it expires.
Frequently asked questions
- What does this tool show?
- The certificate’s issuer, validity dates, and days remaining until expiry for the domain’s HTTPS endpoint.
- What happens if my SSL certificate expires?
- Browsers show a full-page security warning and block the site, which visitors experience as downtime. Renew before the expiry date to avoid it.
- Why does a valid certificate still trigger a warning?
- Common causes are a hostname mismatch, a missing intermediate certificate in the chain, or an untrusted issuer — not just expiry.
- Can Domnr watch certificate expiry for me?
- Yes — Domnr tracks SSL validity and expiry across all your domains and alerts you before a certificate lapses.