What does an SSL certificate checker do?

It connects to a website on port 443, retrieves its SSL/TLS certificate and shows the details: who issued it, which domains it covers, when it was issued and when it expires.

Subject Alternative Names are the extra domain names a single certificate covers, for example www.example.com alongside example.com. This tool lists them all.

WEBSITE SECURITY TOOLS · FREE ONLINE TOOL

SSL Certificate Checker

Verify any site's SSL certificate, expiry, issuer and validityAn expired certificate turns a working website into a full-page browser warning overnight, and it still happens to major sites every year. Enter any domain to see the dates, issuer, and covered domains in seconds.

✓ Free to use✓ No sign-up✓ Ready in your browser

// SSL CERTIFICATE CHECKER · GET STARTED

Use SSL Certificate Checker

Verify any site's SSL certificate, expiry, issuer and validity

// SSL CERTIFICATE CHECKER · HOW IT WORKS

How to use the SSL Certificate Checker

Enter domain

Enter the domain or hostname (e.g. example.com).

Check certificate

Click "Check SSL certificate".

Review validity

Review the validity status, expiry date, issuer and covered domains.

// SSL CERTIFICATE CHECKER · ABOUT THIS TOOL

About the SSL Certificate Checker

An expired SSL certificate turns your site into a browser warning page overnight. The SSL Certificate Checker opens a real TLS connection to any host and reports the details that matter: validity window, days remaining, issuer, and every domain the certificate covers. Run it on your own domains as a renewal reminder, or on any site to verify its certificate is genuine and current before you trust it with sensitive data.

Where it helps most

Looking at the date before the browser does.

Renewal reminders

Check days remaining regularly so expiry never blindsides you or your visitors.

Post-renewal sanity checks

Confirm the new certificate actually took effect right after a renewal completes.

Pre-payment verification

Verify a site's certificate is genuine and current before trusting it with payment details.

Understanding certificate types

See whether a site uses domain, organization, or extended validation, and what that trust means.

Reading the report

The details that actually matter.

Days remaining

The validity window with days left until expiry, the number that prevents the overnight outage.

SHA-256 fingerprint

A unique hash of the certificate; comparing it over time detects man-in-the-middle attacks or swaps.

Covered domains

The Subject Alternative Names list confirms www, root, and every variant you serve is protected.

SSL Certificate Checker: built for trust

It takes seconds and needs no signup: open a real TLS connection and read the certificate details that matter.

// SSL CERTIFICATE CHECKER · COMMON QUESTIONS

SSL Certificate Checker FAQs

How do I check when my website's SSL certificate expires?

Enter your domain here and you will instantly see the exact expiry date plus days remaining, along with the issuer and every domain the certificate covers. No signup needed.

What is the SHA-256 fingerprint?

What are SANs?

What happens if my SSL certificate expires?

Why do SSL certificates expire at all?

How often should I check my SSL certificate?

tools-guide

SSL Certificate Checker: Verify Expiry and Validity Free

Free SSL certificate checker: verify any website's certificate issuer, expiry date, days remaining, covered domains and fingerprint. Avoid expiry outages.

Read article →