What is an SSL Certificate?
An SSL/TLS certificate enables encrypted (HTTPS) connections between a user's browser and a website. It ensures that data transmitted cannot be intercepted or modified.
What we check
- Validity — Is the certificate currently valid and not expired?
- Issuer — Who issued the certificate (Let's Encrypt, DigiCert, Sectigo, etc.)
- Subject — Which domain(s) the certificate covers
- SANs — Subject Alternative Names — additional domains covered
- Expiry date — When the certificate needs renewal
Types of SSL Certificates
| Type | Validation | Trust Level |
|---|---|---|
| DV (Domain Validated) | Automated, proves domain control | Basic |
| OV (Organization Validated) | Verifies the organization exists | Medium |
| EV (Extended Validation) | Thorough legal verification | Highest |
Common Issues
- Expired certificate — Site shows security warning
- Mismatched domain — Certificate doesn't cover the accessed domain
- Self-signed — Not trusted by browsers
- Mixed content — HTTPS page loads HTTP resources
Let's Encrypt
Most websites today use Let's Encrypt, a free certificate authority. Certificates are valid for 90 days and auto-renewed.