About the SSL Certificate Checker
The SSL certificate checker opens a TLS connection to a public hostname and summarizes the certificate presented by that endpoint. Use it to confirm names, issuer, validity dates, protocol details, and the remaining time before expiration.
How to use this tool
Enter a hostname without a URL path and run the check. Use the exact hostname visitors connect to, because example.com and www.example.com can terminate TLS separately. Compare the reported subject alternative names with the requested hostname and confirm that the current time falls between the not-before and not-after dates. Recheck after a certificate renewal or load-balancer change to ensure the intended certificate is being served publicly.
How to read the result
A valid certificate must be within its validity window and cover the requested hostname, normally through a Subject Alternative Name. The issuer identifies the certificate authority or intermediate that signed it. Days remaining helps plan renewal but does not confirm that automation will succeed. Protocol and cipher fields describe the negotiated connection from the checker. The serial number and fingerprint can help distinguish certificates during a rotation.
Limits and privacy
This is an external point-in-time connection from buffer.lol, so it cannot inspect certificates available only on private networks or behind client authentication. A successful handshake does not audit every supported TLS version, cipher, certificate-chain path, or browser. CDN and load-balanced endpoints may present different certificates by location. The submitted hostname is processed by the server-backed checker and private or reserved targets are rejected.
Common questions
- Does a valid certificate mean the website is secure?
- No. It confirms aspects of the TLS identity and validity window, not the security of the application, server, or content.
- Why does the checker show a different certificate than expected?
- DNS, CDN routing, load balancing, SNI configuration, or an incomplete deployment can direct the checker to a different TLS endpoint.