SSL Checker
Inspect TLS and SSL certificate details, validity dates, subject alternative names, and cipher parameters for any hostname and port.
Run tool
Inspect the TLS certificate of any accessible server by connecting over the network to evaluate certificate metadata and handshake properties. Enter a target hostname and an optional port number to initiate the check. The tool connects using a standard network request with a ten-second connection timeout, negotiates the TLS handshake, and retrieves the certificate data. After the connection completes, the result panel shows the certificate subject, issuing authority, serial identifier, validity date range, and alternative hostnames. If the certificate validity dates are readable, the report also indicates whether the certificate is currently valid and calculates the remaining validity in whole days. You will also see connection parameters including the negotiated TLS protocol version and active cipher details. If the hostname cannot be resolved, the connection is refused, or the certificate check encounters a network timeout, the result panel displays the specific diagnostic error.
Instructions
- Enter the target domain name or hostname in the Host field.
- Enter the network port number, or leave it set to the default port 443.
- Run the check to establish the connection and inspect the TLS certificate details.
Examples
- Check a standard HTTPS web server: Enter host example.com and port 443 to retrieve its TLS certificate validity dates, issuer, and cipher suite.
- Inspect a custom secure service: Enter host mail.example.com and port 8443 to verify subject alternative names and calculate remaining days before expiration.
FAQ
What happens if a domain or port cannot be reached?
If the host cannot be resolved, the connection times out after ten seconds, or the remote server refuses the connection, the result panel displays the specific network or TLS error returned during the attempt.
What default values are used if fields are left empty?
Leaving the host field blank uses example.com as the default. The port field defaults to 443, and any non-numeric port input is automatically treated as 443.
How does the tool calculate certificate expiration?
When certificate validity dates are readable, the tool checks whether the certificate is active and computes the remaining validity period in whole calendar days.