SEO & Web ToolsFree

SSL Certificate Checker

Check any domain's SSL/TLS certificate details — expiry date, certificate issuer, subject, Subject Alternative Names (SANs), and whether the certificate is currently valid. Get an alert if the certificate is expired or expiring within 30 days. No signup required.

🌐 API Integration Required

This tool needs a backend API to check external URLs. Options:

  • Use a serverless function (Next.js API route)
  • Integrate with RapidAPI URL checker APIs
  • Use PageSpeed Insights API (for speed checker)

Frequently Asked Questions

What SSL certificate details does this tool show?▼
Expiry date, days until expiry (or days since expiry if expired), certificate issuer (CA name), domain subject, Subject Alternative Names (SANs), and whether the certificate is currently valid.
Does an expired SSL certificate affect SEO?▼
Yes. Google Chrome and all major browsers display security warnings for sites with expired SSL certificates, causing most visitors to leave immediately. Google also considers HTTPS a ranking signal.
How far in advance should I renew my SSL certificate?▼
Renew 30-60 days before expiry. Let's Encrypt certificates are valid for 90 days; commercial certificates are typically valid for 1 year. Set a calendar reminder well before expiry.
What is a Subject Alternative Name (SAN)?▼
SANs list all the domain names covered by a single certificate. A SAN certificate for example.com might also cover www.example.com, api.example.com, and mail.example.com.
Why would a valid certificate show as invalid?▼
Common reasons: the certificate does not cover the domain being checked (missing SAN), the certificate is self-signed, the certificate chain is incomplete, or the intermediate CA is not trusted.