SSL Checker
Inspect the current TLS certificate for any domain — issuer, validity, SANs.
About the SSL Certificate Checker
The SSL Certificate Checker inspects the TLS certificate served by any HTTPS site or domain — showing you the issuer, valid-from and expiry dates, subject name and Subject Alternative Names (SANs), key algorithm and size, signature algorithm, and whether the certificate is trusted, self-signed or expired. It also flags certificates that are about to expire, use weak algorithms (SHA-1), or lack the correct SANs for the hostname.
SSL/TLS expiry is one of the top causes of unplanned outages — an expired certificate takes an entire service offline for every user until it's renewed. Automated monitoring (like this tool) is essential. Beyond expiry, you need to verify that the correct hostname is covered by the certificate's SANs — a common issue when adding new subdomains to a system with a manually renewed cert.
DevOps engineers, SREs, security teams and web admins run SSL checks continuously — either through automated monitors or on-demand when investigating an incident. Combine with our HTTP Headers tool to verify HSTS is set (which locks browsers to HTTPS for repeat visitors) and CAA-record lookup to confirm your issuance policy is correctly published.
How to use this tool
- 1Enter the required value in the input field above (domain, IP, URL, or text depending on the tool).
- 2Click the action button to run the check — results are computed instantly from our edge network.
- 3Review the parsed output, key fields and any warnings shown in the result card.
- 4Copy the result, share the page URL, or jump to a related tool from the sidebar to continue debugging.
Key features
- Issuer, subject, SANs and validity dates
- Key algorithm and size
- Expiry countdown with warnings
- Detects weak signature algorithms