🔒

SSL/TLS Checker

Validate the active SSL certificate chain, identifying expiry dates, issuing authorities, and trusted root status.

PROTOCOL: HTTPS
CRYPTOGRAPHY: RSA/ECDSA, SHA-256
IDENTITY: SAN (Subject Alternative Names)

What is SSL/TLS Checker?

SSL/TLS Checker mathematically validates the digital passport (the certificate) a website uses to prove its identity and securely encrypt data ranging from passwords to credit cards.

How it Works

It initiates a raw cryptographic TLS handshake, pulling down the server's leaf certificate along with its intermediate chain. It checks the expiration date and mathematically walks the chain up to a globally trusted Root CA.

Key Use Cases

Receiving proactive alerts before a critical corporate certificate expires and causes a global outage.

Discovering if a web host accidentally broke the "certificate chain" causing errors on old Android phones.

Verifying that a certificate successfully covers all required root and wildcards subdomains via the SAN list.

Advanced Details

Even if a Leaf Certificate is perfectly valid, if the server forgets to serve the "Intermediate Certificate" alongside it, browsers will throw an "Untrusted Connection" red warning.

Cybersecurity Pros & Cons

Security Advantages
  • Expired certificate detection prevents sudden HTTPS outages that displace users to HTTP, exposing credentials in plaintext.
  • SAN list inspection ensures wildcard certificates correctly cover all intended subdomains without accidental gaps.
  • Certificate chain validation confirms the full trust path to a recognised Root CA — broken chains cause errors on strict mobile clients.
  • Signature algorithm audit (SHA-1 vs SHA-256) identifies weak legacy certificates that need urgent replacement.
Security Limitations
  • A valid SSL certificate provides no assurance about the website's content — phishing sites routinely obtain free, valid SSL certs.
  • Certificate Transparency Logs mean every certificate issued is publicly visible — exposing internal subdomain names.
  • Wildcard certificates (*.domain.com) create a single point of failure — one compromised server can expose all subdomains.
  • Certificate pinning implementation failures leave apps vulnerable even after a certificate compromise is detected and replaced.
Ready to Test?

Use our professional-grade tool to perform a real-time check for this module.

Run Module Now
Related Docs