The SSL Certificate Expiration Checker is designed to quickly check the validity period and expiration time of website HTTPS certificates. Enter one or more domains or IP addresses to perform batch SSL/TLS certificate checks and view remaining days, valid-from dates, expiration dates, and result statistics.
The tool calculates the current certificate status and remaining validity based on the SSL/TLS certificate actually returned by each server. Results are categorized as valid, expiring soon, expired, or failed, helping you quickly identify HTTPS certificates that require renewal.
Remaining days represent the validity period between the current check time and the certificate expiration time. This makes it easy to identify websites that need certificate renewal or replacement in advance.
The expiration time is the exact point when an SSL certificate stops being valid. Websites, APIs, and other HTTPS services in production should complete renewal and deployment before this time to avoid HTTPS connection problems.
In addition to checking individual websites, this tool supports batch checks of multiple targets. You can submit multiple domains or IP addresses at once and inspect several HTTPS services together, making it useful for website operations, server administration, and certificate inventory management.
After batch checking is complete, the tool summarizes the results, including the total number of certificates, valid certificates, certificates expiring soon, expired certificates, and failed checks.
443.Certificates approaching expiration should be prioritized for renewal. For business-critical websites, do not wait until the final few days because DNS, CDN, load balancer, or server deployment issues may delay the update.
After an SSL certificate expires, browsers and other TLS clients may reject a trusted HTTPS connection and display certificate expiration or connection security warnings. API services may also experience failed client requests.
A failed check does not necessarily mean that the SSL certificate has expired. It may be caused by an unreachable server, a closed port, TLS handshake failure, network restrictions, or server configuration problems. Failed targets should be investigated separately.
HTTPS certificates have defined validity periods. When many websites are managed, manually checking each certificate can easily result in missed expiration dates. Regular batch checks provide a centralized way to identify certificate risks and schedule renewal and deployment in advance.
Teams maintaining multiple websites, API domains, servers, or business systems can use batch SSL certificate checks to maintain a certificate list and regularly review remaining validity, reducing service interruptions caused by expired certificates.
SSL certificate expiration checking focuses on certificate lifecycle management, including current status, remaining days, valid-from time, and expiration time, and is suitable for checking multiple targets. SSL certificate checking focuses more on detailed X.509 information such as subject, issuer, serial number, signature algorithm, and public key.
If the main goal is to determine when a certificate expires, how many days remain, or to check multiple websites at once, use the SSL Certificate Expiration Checker. If you need detailed information about the certificate subject, issuing authority, signature algorithm, or public key, use an SSL Certificate Checker instead.
Remaining days are calculated from the difference between the check time and the certificate Not After expiration time. Because certificates have a precise expiration timestamp, the remaining number of days continuously decreases over time.
A certificate remains valid until its expiration time, but a short remaining validity period means renewal should be scheduled soon. The tool uses the “Expiring soon” status to identify these certificates.
Failed targets may be unable to establish a TCP connection or TLS handshake. Incorrect ports, server restrictions, unreachable networks, or TLS configuration problems can also cause failures. These targets should be investigated separately.
After batch checking is complete, the results can be exported for organizing SSL certificate assets, maintaining expiration lists, and performing subsequent operational management.
The SSL Certificate Expiration Checker is suitable for website administrators, server operators, developers, and security professionals. Regular batch checks can identify certificates that are approaching expiration or have already expired and help reduce the impact on websites and business systems.
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