🔒 SSL Checker
Inspect any site TLS certificate: issuer, validity dates, days to expiry, SAN list, protocol and trust status.
🔐 The check is performed by a 0Appz server TLS handshake with the public host you provide — no certificate data is stored. Private and internal addresses are blocked.
How to use this tool
Overview
SSL Checker - Free TLS Certificate & Expiry Inspector inspects the TLS certificate behind any HTTPS site. Enter a domain and the tool performs a real handshake from a 0Appz server: you get the certificate subject and issuer, the exact validity window, the days remaining before expiry (highlighted when under 30 days), the full Subject Alternative Names list, the serial number and signature algorithm — plus the negotiated TLS version and cipher suite. A second verified connection tells you whether browsers would trust the certificate, so self-signed, expired, hostname-mismatched and incomplete-chain certificates are flagged clearly instead of failing silently. Ideal for confirming renewals went through, debugging "not secure" warnings, auditing vendor sites and checking certificates before a launch.Frequently asked questions
How does the SSL check work? +
A 0Appz server opens a TLS connection to your domain on port 443 (or a custom port) and reads the presented certificate — subject, issuer, validity window, SAN list — plus the negotiated protocol and cipher. A second, verified connection determines whether browsers would trust it. Nothing is stored beyond a one-hour result cache.
What does "not trusted" mean? +
The certificate did not pass standard browser verification: it may be self-signed, issued by an unknown authority, expired, or missing an intermediate certificate. Browsers show a full-page warning for such sites. The tool connects with verification disabled on purpose so it can still show you the details.
What are SANs? +
Subject Alternative Names list every hostname the certificate is valid for — for example example.com and www.example.com. If your domain is not in the SAN list (and does not match a wildcard entry), browsers will report a name mismatch.
Can I check internal servers? +
No. Private, loopback and reserved IP ranges are blocked to prevent server-side request forgery (SSRF). Only publicly reachable hosts can be checked.