How to Check SSL Certificate Expiration

Why SSL Certificate Expiration Matters

SSL certificates encrypt data between servers and visitors, protect sensitive information such as login credentials or payment details, and validate the authenticity of your website. When a certificate expires, browsers display warnings, which can cause users to lose trust, interrupt transactions, and even affect SEO rankings. Monitoring SSL expiration ensures uninterrupted access, maintains user trust, and reduces compliance risks.

How to Check SSL Certificate Expiration

1. Using Your Browser

Modern browsers allow quick inspection of SSL certificates:

• Click the padlock icon in the address bar.
• Select \"Connection is secure\" or \"Certificate\" details.
• Check the \"Valid from\" and \"Valid until\" dates.

While convenient, this method is not scalable for multiple sites.

2. Using Command-Line Tools

Command-line tools provide detailed certificate information:

openssl s_client -connect example.com:443 -servername example.com < /dev/null | openssl x509 -noout -dates

This shows the certificate's notBefore and notAfter dates.

On Windows, PowerShell can be used:

Get-ChildItem -Path Cert:\\LocalMachine\\My | Where-Object {$_.NotAfter -lt (Get-Date).AddDays(30)}

This lists certificates expiring within 30 days.

3. Using Online SSL Checkers

Online tools make it easy to verify expiration dates and diagnose certificate issues:

• ScanTower Free SSL Checker – Fast, accurate certificate inspection with expiration details, chain validation, hostname matching, and security-grade reporting.
• SSL Labs – Full deep-dive report on certificate configuration, chain structure, supported ciphers, and TLS settings.
• Why No Padlock – Useful for identifying insecure elements such as mixed content and incomplete certificate chains.

4. Automated Monitoring Solutions

Manual checks are error-prone. Automated monitoring platforms, such as ScanTower, provide:

• Continuous monitoring of multiple domains and servers.
• Alerts well before certificates expire.
• Tracking of full certificate chains and TLS configuration drift.
• DevOps-friendly workflows with integrations and API support.

Best Practices for SSL Certificate Management

• Set proactive alerts: Receive notifications at least 30 days before expiration.
• Automate renewal: Use ACME protocol or vendor automation.
• Maintain an inventory: Track all certificates, including intermediate and root certificates.
• Regularly validate: Check certificate configuration, supported ciphers, and TLS versions.
• Document renewal procedures: Ensure your team knows manual renewal steps in case automation fails.

Conclusion

SSL certificate expiration leads to downtime, security warnings, and broken user trust. Using browser tools, command-line checks, online scanners, and automated monitoring services like ScanTower gives you complete visibility and ensures your certificates never lapse.