How to verify if a certificate is valid?


Editorial team Published on

You can quickly verify an SSL/TLS website certificate by clicking the lock icon next to the URL in your web browser's address bar and selecting Certificate Information or View Certificate.

Browser Verification

  • Click the Lock: Look for the padlock symbol on the left side of the web address bar.
  • Open Details: Select connection details and open the certificate viewer.
  • Check Expiry & Domain: Confirm that the current date falls within the validity period ("Valid From" and "Valid To") and that the domain name matches the site you are visiting.
  • Check the Issuer: Verify that a trusted Certificate Authority (CA) signed the certificate.

Online Tools

  • Use online diagnostic utilities like the SSL Shopper SSL Checker to test if a remote server's public hostname has a valid and correctly installed certificate.
  • Run deep cryptographic and configuration tests using the Qualys SSL Labs Test.

Command-Line Verification

  • Check via cURL: Run curl -Iv https://example.com in your terminal to inspect the active certificate expiration and handshake details without browser caching.
  • Check via OpenSSL: Run openssl s_client -connect hostname:443 -showcerts to display the full certificate chain.
  • Verify against a CA: Run openssl verify -verbose -CAfile cacert.pem server.crt to cryptographically confirm that a local certificate file was signed by a specific trusted issuer.