Free SSL Certificate Checker & Validator
Instantly check SSL certificate validity, expiry date, issuer, protocol, and cipher suite for any domain or URL
How to Check & Monitor SSL Certificates
An SSL/TLS certificate encrypts data between your server and users' browsers, proves your site's identity, and enables the HTTPS padlock that users trust. This free SSL certificate checker lets you instantly verify any domain's SSL status — including validity, expiration date, issuer, TLS protocol version, cipher suite, and key size — without needing an account. Enter a domain or URL above to get results in seconds.
Why SSL Certificate Monitoring Matters
- Security: Encrypts sensitive data in transit — passwords, payment info, personal data
- Trust: Browsers show a padlock for valid HTTPS; a warning page for expired or invalid certs
- SEO: Google uses HTTPS as a ranking signal — HTTP sites rank lower
- Compliance: Required for PCI DSS, GDPR, HIPAA, and other data security standards
SSL Certificate Types
- Domain Validated (DV): Verifies domain ownership only — issued in minutes, suitable for most websites
- Organization Validated (OV): Verifies domain + organization identity — adds business credibility
- Extended Validation (EV): Highest assurance level — requires thorough vetting of the organization
Common SSL Certificate Issues
- Expired certificate: The certificate's validity date has passed — browsers block access immediately
- Domain mismatch: The certificate was issued for a different domain name — triggers browser warning
- Untrusted issuer: The Certificate Authority (CA) is not trusted by browsers — self-signed certs
- Mixed content: HTTPS page loading HTTP resources (images, scripts) — browsers flag as insecure
SSL Certificate Best Practices
- Set up SSL expiry monitoring with automated alerts at least 30 days before expiration
- Use automated renewal with Let's Encrypt or your CA's ACME protocol
- Implement HSTS (HTTP Strict Transport Security) headers to force HTTPS
- Use TLS 1.2 or 1.3 — disable older SSL/TLS versions (SSL 3.0, TLS 1.0, TLS 1.1)
- Prefer 2048-bit or 4096-bit RSA keys, or ECDSA for better performance
- Use wildcard or multi-domain (SAN) certificates to cover all subdomains
Frequently Asked Questions
How do I check my SSL certificate?
Enter your domain or URL (e.g. example.com or https://example.com) in the field above and click 'Check SSL Certificate'. This free tool instantly shows your certificate's validity status, expiration date, issuer, TLS protocol, cipher suite, and key size.
How do I check when my SSL certificate expires?
This checker shows the exact expiry date and the number of days remaining. If your certificate has fewer than 30 days left, you should renew it immediately. For automated SSL expiry monitoring with email alerts, use AlertSleep — it checks your certificate daily and notifies you before it expires.
What happens if my SSL certificate expires?
All major browsers (Chrome, Firefox, Safari) immediately show a full-screen security warning blocking access to your site. Users cannot bypass this easily. Search engines may also delist or downrank your pages. Expired SSL certificates can kill your traffic and revenue within hours.
How do I get SSL certificate expiry alerts?
AlertSleep's SSL monitoring checks your certificate every day and sends you email (or Slack/Telegram) alerts when your certificate is about to expire — configurable at 30, 14, or 7 days before expiry. Sign up free to monitor up to 5 domains.
What is SSL certificate monitoring?
SSL certificate monitoring is an automated service that regularly checks your certificates for validity, upcoming expiration, and configuration issues. It alerts you before your certificate expires — preventing the outages and trust warnings that come with an expired SSL cert.
How often should I check my SSL certificate?
For manual checks, monthly is good practice. For production websites, automated daily monitoring is essential — certificates can expire without warning if auto-renewal fails. AlertSleep checks your SSL status every 24 hours and alerts you before expiry.
Can I get a free SSL certificate?
Yes. Let's Encrypt provides free SSL/TLS certificates with 90-day validity and automated renewal via the ACME protocol. Most major hosting providers (cPanel, Cloudflare, Nginx, Apache) support Let's Encrypt natively. Free certificates are DV (Domain Validated) level.
What is a wildcard SSL certificate?
A wildcard certificate (e.g. *.example.com) secures a domain and all its first-level subdomains — app.example.com, api.example.com, blog.example.com, etc. — with a single certificate. It does not cover second-level subdomains (e.g. app.api.example.com).
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