SSL Certificate Checker

What is an SSL certificate checker?

SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) encrypt the connection between a web browser and a server, protecting data in transit from eavesdropping and tampering. An SSL certificate proves that a website is who it claims to be. This tool checks whether a domain's SSL certificate is valid, properly configured, and not expired.

When you visit a website with HTTPS, your browser verifies the SSL certificate before establishing the encrypted connection. If the certificate is expired, issued for a different domain, or signed by an untrusted authority, the browser displays a security warning. This tool performs the same checks and provides detailed information about the certificate.

What this tool checks

• Certificate validity — whether the certificate is currently valid and not expired.
• Domain match — whether the certificate covers the domain you entered.
• Certificate chain — whether the chain of trust from the certificate to a root CA is complete.
• Expiration date — how many days until the certificate expires.
• Issuer information — which Certificate Authority issued the certificate.

How to use this tool

Enter a domain name (like example.com) and the tool connects to the server, retrieves the SSL certificate, and displays its details. You will see the subject, issuer, validity dates, certificate type (DV, OV, EV), and any configuration issues. Use this to monitor your own certificates or verify that a website you plan to share data with is properly secured.

Certificate types

Domain Validation (DV) certificates only verify domain ownership and are the most common (used by Let's Encrypt). Organization Validation (OV) certificates verify the organization behind the domain. Extended Validation (EV) certificates require the most thorough verification. All three provide the same level of encryption — the difference is in the identity verification of the certificate holder.

Frequently asked questions

What happens when an SSL certificate expires?

Browsers display a prominent security warning that discourages visitors from proceeding. Most users will leave rather than bypass the warning, causing significant traffic loss. Search engines may also demote the site in rankings. Modern tools like Let's Encrypt and Certbot automate renewal to prevent accidental expiration.

Is SSL the same as TLS?

SSL is the older protocol (last version: SSL 3.0 from 1996). TLS is the modern successor (current: TLS 1.3). All SSL versions are now considered insecure and deprecated. When people say SSL today, they usually mean TLS. Certificates are still commonly called SSL certificates even though they use TLS for the actual encryption.