What is SSL/TLS?

SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are cryptographic protocols that provide secure communication over the internet. They encrypt data transmitted between a web browser and a server, ensuring that sensitive information — such as passwords, credit card numbers, and personal data — cannot be intercepted or tampered with by third parties.

When a website uses SSL/TLS, the URL begins with "https://" instead of "http://," and browsers display a padlock icon in the address bar. This indicates that the connection is encrypted and that the server's identity has been verified through a digital certificate issued by a trusted Certificate Authority (CA).

SSL/TLS certificates contain the server's public key, the domain name, the certificate issuer, and an expiration date. When a browser connects to an HTTPS site, it performs a "handshake" to verify the certificate's validity and establish an encrypted session.

SSL/TLS is essential for security, trust, and SEO. Any website that handles user data — login forms, payment pages, or contact forms — must use HTTPS to prevent man-in-the-middle attacks. Without encryption, data sent between the user and the server is transmitted in plain text and can be read by anyone on the same network.

Google Chrome marks all HTTP pages as "Not Secure," which deters visitors and damages trust. Google also uses HTTPS as a ranking signal — sites with valid SSL certificates rank higher than their unencrypted counterparts. Additionally, many modern web features (like service workers, geolocation, and payment APIs) require HTTPS to function.

An expired or misconfigured SSL certificate can cause browsers to display full-page security warnings, effectively blocking users from accessing your site until the issue is resolved. This makes SSL certificate monitoring a critical part of website maintenance.

WebCheckly's SSL certificate detection checks the validity, issuer, expiration date, and SAN (Subject Alternative Name) list of any domain's certificate. You can verify whether your certificate is properly configured, how many days remain before expiration, and whether all required domain names are covered.

WebCheckly also provides continuous SSL expiry monitoring with configurable warning thresholds. When your certificate is approaching expiration, WebCheckly sends alert notifications so you can renew before it expires. This prevents unexpected certificate expiration — one of the most common causes of HTTPS-related downtime.

• Website Availability — SSL expiry can cause availability issues and security warnings.
• HTTP Status Codes — SSL errors produce specific status codes and connection failures.
• Technical SEO — HTTPS is a confirmed Google ranking signal.