SSL Checker

What is the SSL Checker?

The SSL Checker opens a live TLS connection to a public domain and inspects the certificate that server presents at that moment. It independently records the certificate details and performs a browser-style verified handshake using the server's public trust store.

The report separates public trust, hostname coverage, validity dates, and the negotiated connection. It is a focused certificate and handshake check—not a full cipher inventory, vulnerability scan, Certificate Transparency history search, revocation monitor, or permanent uptime monitor.

How to check an SSL/TLS certificate

1. Enter a public domain or an HTTP/HTTPS website URL. A port included in the URL is recognized when it is supported.
2. Choose the TLS port. Port 443 is correct for almost every HTTPS website; common alternate HTTPS ports are also available.
3. Select Check SSL. The server resolves the domain safely and performs live unverified and verified TLS handshakes to the same public address.
4. Review the trust, hostname, validity and TLS checks, then open Certificate or Connection & SANs for technical details.
5. Copy the plain-language report or export the exact result as JSON for troubleshooting and renewal records.

A clearer SSL certificate report

• Shows invalid, expired, not-yet-valid, hostname-mismatch, untrusted, and renewal-warning states distinctly.
• Uses a verified TLS client context for public trust and hostname validation while still retrieving details from invalid certificates.
• Lists certificate subject, issuer, validity window, serial number, SAN coverage, and SHA-256 fingerprint.
• Reports the exact TLS version, selected cipher, encryption bits, ALPN protocol, server address, and port used by this connection.
• Blocks IP literals, private or reserved DNS targets, and arbitrary ports to prevent internal-network and port-scanning misuse.

SSL Checker FAQ