SSL Certificate Checker
Free SSL certificate checker. Check any website's SSL certificate details. Essential for security monitoring.
Enter a domain and click Check SSL.
How to Use SSL Certificate Checker
Enter a Domain
Type any domain name to check its SSL certificate.
View Certificate Details
Certificate info is displayed: issuer, valid dates, subject, and serial number.
Frequently Asked Questions
What is an SSL certificate?
An SSL certificate authenticates a website and enables encrypted HTTPS connections. Issued by Certificate Authorities, they have expiration dates and must be renewed.
Why do SSL certificates expire?
Certificates expire to limit the impact of compromised keys. Most last 90 days to 1 year. Let's Encrypt issues 90-day certificates designed for auto-renewal.
How do I check my own certificate?
Enter your domain in this tool. For production monitoring, set up automated alerts before certificates expire.
SSL Certificate Basics
SSL/TLS certificates use public key cryptography for secure connections. When visiting an HTTPS site, the server presents its certificate. Your browser verifies it against trusted CAs and establishes an encrypted session.
Key fields: Subject (domain), Issuer (CA), Valid From/To (validity period), Serial Number (unique ID). Wildcard certificates cover *.example.com and all subdomains.