SSL/TLS Certificate Analyzer
Analyze SSL/TLS certificates for any domain. Check validity, certificate chain, protocol support, and security grade.
How to Use the SSL Certificate Analyzer
- Enter the domain name you want to analyze (e.g., example.com).
- The tool connects to the server and retrieves the SSL/TLS certificate and configuration.
- Review the certificate details: issuer, validity dates, subject, and SANs.
- Check the protocol support (TLS 1.2, TLS 1.3) and cipher suite configuration.
- Review the overall security grade and act on any identified weaknesses.
Understanding SSL/TLS Certificates
SSL/TLS certificates are digital certificates that authenticate a server's identity and enable encrypted communication between clients and servers. When you visit a website over HTTPS, the browser verifies the server's certificate against trusted Certificate Authorities (CAs), checks that the certificate has not expired or been revoked, and then establishes an encrypted connection using the negotiated TLS protocol version and cipher suite. A certificate contains the domain name (and Subject Alternative Names for additional domains), the public key, the issuing CA's signature, validity period, and various extensions. The certificate chain includes the server certificate, any intermediate certificates, and the root CA certificate. All links in the chain must be valid for the browser to trust the connection. Common issues include expired certificates, incomplete chains (missing intermediates), and certificates issued for the wrong domain. TLS configuration security depends on more than just having a valid certificate. The server must support modern protocol versions (TLS 1.2 minimum, TLS 1.3 preferred) and disable legacy versions (SSL 3.0, TLS 1.0, TLS 1.1) that have known vulnerabilities like POODLE and BEAST. Cipher suite selection matters: prefer AEAD ciphers (AES-GCM, ChaCha20-Poly1305) and forward secrecy (ECDHE key exchange). Weak ciphers (RC4, DES, export-grade) must be disabled. Certificate Transparency (CT) logs provide an additional layer of accountability by publicly logging all issued certificates.
Frequently Asked Questions
Your server should support TLS 1.2 and TLS 1.3. Disable TLS 1.0 and TLS 1.1, which were deprecated in 2021 due to known vulnerabilities. TLS 1.3 is significantly faster and more secure, eliminating many legacy features that caused vulnerabilities in older versions. Most modern browsers require TLS 1.2 or higher.
The certificate chain links your server's certificate to a trusted root CA through intermediate certificates. If the chain is incomplete (missing intermediates), some clients will fail to validate the certificate even though it is legitimate. Always configure your server to send the complete chain. You can verify this with this tool.
Forward secrecy (also called Perfect Forward Secrecy or PFS) ensures that session keys are not compromised even if the server's private key is later stolen. ECDHE and DHE key exchanges provide forward secrecy by generating unique keys for each session. Without it, an attacker who captures encrypted traffic and later obtains the private key can decrypt all past sessions.
Certificate lifetimes have been shortened for security reasons. The current maximum is 398 days (13 months). Let's Encrypt certificates are valid for 90 days, encouraging automated renewal. Use automated tools like certbot to handle renewal. Expired certificates cause immediate browser warnings and loss of user trust.