SSL Certificate Checker
Check HTTPS connectivity, HSTS configuration, and TLS security for any domain.
What is an SSL Certificate?
SSL/TLS certificates encrypt the connection between your browser and a website, ensuring data privacy and integrity. A valid certificate confirms the website's identity and enables the HTTPS padlock icon. Expired or misconfigured certificates create security warnings that drive visitors away.
Why check your SSL certificate?
An expired or misconfigured SSL certificate is one of the fastest ways to lose visitor trust. Browsers will display a full-page warning, and Google treats HTTPS as a ranking signal — so a broken certificate can hurt both traffic and SEO.
Common SSL issues
- Expired certificate — browsers block access entirely until renewed
- Certificate name mismatch — the domain on the cert doesn't match your URL
- Incomplete certificate chain — missing intermediate certificates cause trust errors
- Mixed content — loading HTTP resources on an HTTPS page triggers warnings
- Weak protocols — older TLS versions (1.0, 1.1) are considered insecure
Tips
- Set a calendar reminder 30 days before expiry — or use auto-renewing certs (e.g. Let's Encrypt)
- Always include the full certificate chain when installing your cert
- Enforce TLS 1.2+ and disable older protocols on your server
- Use HSTS headers to tell browsers to always use HTTPS
- Check all subdomains too — a wildcard cert covers
*.example.combut not the root
Frequently Asked Questions
What is an SSL certificate?
An SSL/TLS certificate is a digital credential that encrypts data between a browser and a web server. It authenticates the website's identity and enables HTTPS, protecting user data from interception or tampering in transit.
How do I know if my SSL certificate is valid?
A valid certificate shows a padlock in the browser address bar, serves the site over HTTPS, has a domain name that matches the certificate, and has not expired. This tool checks all of those automatically.
What happens if my SSL certificate expires?
Browsers display a security warning that blocks most visitors, causing an immediate drop in traffic and trust. Google also uses HTTPS as a ranking signal, so an expired cert can negatively affect your search rankings.
What is HSTS and why does it matter?
HSTS (HTTP Strict Transport Security) is a security header that tells browsers to always connect to your site over HTTPS, even if a user types http://. It prevents downgrade attacks and cookie hijacking over insecure connections.