Check an HTTPS certificate on port 443. Review issuer, expiry dates, SANs, certificate chain, TLS version, cipher, fingerprint, key details and HSTS status.
An SSL Checker inspects the certificate that a hostname currently presents during a TLS connection. Enter a domain or HTTPS address to see its certificate status, expiry countdown, issuer, validity dates, Subject Alternative Names, certificate chain, TLS version, cipher, key details, and other published certificate information. It is designed for certificate configuration checks before renewal, after deployment, or when a browser shows a “connection is not private” warning. The report is most useful when the hostname, active endpoint, and certificate details are reviewed together.
SSL is the older name commonly used for the certificate layer; modern HTTPS connections use TLS. This tool reads the certificate served on port 443 and reports what it can inspect from that connection. It is not a general website security audit, vulnerability scanner, or guarantee that an application is safe. A certificate can be correctly dated while the website still has insecure code, a weak account policy, or a separate configuration problem.
Enter a hostname or paste a full URL, then select Check SSL. The tool normalizes the input, extracts the host, and opens a TLS connection to port 443. It captures the leaf certificate and any certificate chain sent during the handshake, then reads the certificate fields for the report. A custom port is not available in this page, so services using another TLS port require a separate inspection method.
The certificate is read from the live endpoint rather than from an old database record. That matters when a certificate was renewed on disk but the web server, reverse proxy, CDN, or load balancer is still serving the previous one. The result describes the hostname and endpoint reached by this checker, which may differ from another edge location when a domain uses DNS load balancing or a content delivery network.
The certificate section shows the issuer, valid-from date, valid-to date, days remaining, serial number, certificate version, SHA-256 fingerprint, and signature algorithm. The headline Valid or Invalid status is based on whether the current time falls between the certificate’s validity dates. An expired or not-yet-valid certificate should be renewed or corrected, but a date-valid certificate is not automatically trusted by every browser.
Common Name and Subject Alternative Names help you check hostname coverage. Modern clients normally use SAN entries when deciding whether a certificate covers the requested name, so compare the exact hostname you entered with the displayed list, including the difference between an apex domain and a www subdomain. This page displays CN and SAN values for review; it does not provide a separate automated hostname-match verdict. Wildcards also have scope rules and do not cover every possible subdomain.
After a renewal, check the date, issuer, SAN list, fingerprint, and chain together. A new certificate may be valid while an old certificate is still active on one load balancer, a staging listener, or a CDN edge. If different visitors report different warnings, compare the hostname and endpoint they reach rather than assuming that one successful check represents every TLS termination point.
The server section reports the resolved server IP, negotiated TLS version, cipher suite, public-key algorithm, and key size. These details help explain whether the endpoint completed a TLS handshake and what cryptographic parameters it presented. They do not rate the complete security of the server, and a familiar cipher or modern protocol does not make the application behind HTTPS secure by itself.
The chain view lists certificates received from the endpoint with their subject, issuer, and expiry date when chain data is available. A missing intermediate certificate can create trust errors even when the leaf certificate itself is within its dates. The report also exposes signature and key-usage information, extended key usage, CRL distribution details, and an OCSP-related URL when those extensions exist. It does not perform a live certificate revocation check; these fields are evidence for further review, not a complete trust decision.
The SHA-256 fingerprint is useful for comparing the certificate presented before and after a deployment or renewal. The serial number and issuer add more identifying context when a provider sends several certificates for the same service. Keep fingerprints in an authorised change record, but do not publish private operational notes simply because a certificate is visible to the public; certificate metadata is not a substitute for access control.
Expired certificates, hostname mismatches, self-signed certificates, incomplete chains, unsupported TLS settings, and a wrong certificate served by a proxy can all lead to browser warnings. Compare the issuer, dates, SANs, chain entries, TLS version, and cipher with the hostname and deployment configuration. If the certificate is valid for the root domain but not the subdomain being visited, request or install a certificate that covers the actual names users access.
The checker also reports HSTS status and selected certificate extensions, but it does not prove that every browser will trust the endpoint in every environment. Its TLS context is deliberately suitable for inspecting certificates that may be expired or otherwise invalid, so the displayed date status should not be read as a strict browser trust verdict. A corporate proxy, local trust store, clock problem, CDN edge, or incomplete chain can change what a user sees.
Use the findings with the certificate provider, web-server configuration, reverse proxy, hosting panel, and browser diagnostics. Check that the renewed certificate is installed on the active listener, that the full chain is served, that the SNI hostname selects the intended certificate, and that the server is using the expected TLS configuration. An SSL certificate checker can reveal a configuration mismatch quickly, but it cannot certify the safety, privacy, or business reliability of the whole website.
When a certificate check fails to connect, the cause may be a stopped TLS service, blocked port 443, an incompatible protocol, a firewall, or a hostname that resolves to the wrong endpoint. That failure is different from an expired certificate that was successfully retrieved. Record the error, target hostname, time, and deployment state so the provider or administrator can reproduce the same handshake.