What Is SSL and How to Check a Website's SSL Certificate
Short answer: SSL (Secure Sockets Layer) is the technology that encrypts the connection between your browser and a website, shown by the padlock and https in the address bar. To check a website's SSL certificate for free, use the Bsks SSL Checker: enter the domain, click "Examine SSL", and read the result.
What is SSL?
SSL stands for Secure Sockets Layer. It is a security protocol that encrypts data travelling between a visitor's browser and a website, so passwords, card details and personal information cannot be read if intercepted. Today the term "SSL" usually refers to its successor, TLS — when people talk about an "SSL certificate", they mean the digital certificate that proves a site's identity and enables this encryption. A valid certificate shows visitors the padlock icon and https; an expired or invalid one triggers browser warnings.
How to check a website's SSL certificate in 3 steps
- Enter the domain. Open the SSL Checker and type the domain name into the "Enter a Domain" box.
- Examine it. Click the "Examine SSL" button to inspect the certificate.
- Read the result. The tool reports whether the certificate is valid and trusted, including the certificate chain, expiry date and protocol support.
Practical tips
- Check expiry dates: certificates expire — renew before the date shown so visitors never see a warning.
- Look for full coverage: make sure both the www and non-www versions of your domain are covered by the certificate.
- Fix mixed content: a valid certificate still shows warnings if the page loads images or scripts over plain http — serve everything over https.
- Re-check after changes: run the SSL checker again after renewing or reinstalling a certificate to confirm it is trusted.
Frequently asked questions
What is SSL in simple terms?
SSL is the encryption technology behind the padlock icon in your browser. It scrambles data between you and a website so nobody in between can read it.
What happens if a site's SSL certificate is expired or invalid?
Browsers show a security warning and may block the page. Site owners should renew or reinstall the certificate immediately to restore trust.
Is SSL the same as TLS?
Almost — TLS is the modern successor to SSL. People still say "SSL certificate" out of habit, but the certificates in use today rely on TLS.