SSL Checker

An SSL certificate is a digital certificate that authenticates a website's identity and enables an encrypted connection between a web server and a browser. SSL (Secure Sockets Layer) has been largely replaced by TLS (Transport Layer Security), though the term SSL is still widely used. When installed on a server, the SSL certificate activates the padlock icon and HTTPS protocol in the browser, allowing secure data transfer for sensitive information like login credentials, payment details, and personal data. Certificates are issued by trusted Certificate Authorities after verifying the applicant's identity and domain ownership.

An expired SSL certificate triggers security warnings in web browsers that can scare away visitors and destroy trust. When a certificate expires, browsers display full-page warnings advising users not to proceed, which can cause significant traffic loss. Expired certificates also break the encrypted connection, potentially exposing sensitive user data to interception. Additionally, search engines like Google may lower the ranking of sites with expired certificates. Most certificates are valid for one to two years, so regular monitoring is essential to renew before expiration.

A certificate chain is a hierarchy of certificates that links your server's certificate back to a trusted root Certificate Authority. It typically consists of your end-entity certificate (leaf certificate), one or more intermediate certificates, and the root certificate. When a browser validates your certificate, it must be able to follow this chain of trust all the way to a trusted root. An incomplete chain occurs when intermediate certificates are missing from the server configuration, causing browsers to show security warnings even though your main certificate is valid. Our SSL Checker detects incomplete chains and helps you fix them.

Your server should support TLS 1.2 and TLS 1.3 at minimum. TLS 1.0 and 1.1 are deprecated and considered insecure — major browsers no longer support them. TLS 1.3 is the latest and most secure version, offering improved performance and stronger security. However, TLS 1.2 remains widely used for compatibility with older clients. Disable SSL 2.0, SSL 3.0, TLS 1.0, and TLS 1.1 to ensure your server meets modern security standards and passes compliance audits like PCI DSS.

We recommend checking your SSL certificate at least monthly to ensure it remains valid and properly configured. For production websites handling sensitive data, weekly checks are advisable. Certificate expiration is one of the most common causes of website outages, and it is entirely preventable with regular monitoring. Many organizations use automated monitoring services that alert them 30, 14, and 7 days before expiration. Our free SSL Checker can be used for spot checks whenever you want to verify your certificate status.