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Certificate Transparency Lookup

Discover SSL/TLS certificates, find subdomains, detect phishing sites, and monitor certificate issuance using Certificate Transparency logs.

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How it works:

This tool queries public Certificate Transparency logs to discover all SSL/TLS certificates issued for a domain, including subdomains and historical certificates. Results are cached for 24 hours.

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Understanding Certificate Transparency

Certificate Transparency provides a critical security layer for the web's PKI infrastructure.

Security Use Cases

  • • Detect fraudulent certificates
  • • Monitor unauthorized certificate issuance
  • • Find typosquatting domains
  • • Discover shadow IT and forgotten subdomains
  • • Track certificate expiration dates

Reconnaissance Benefits

  • • Comprehensive subdomain enumeration
  • • Historical certificate data
  • • Identify development/staging environments
  • • Map infrastructure footprint
  • • Discover API endpoints

Frequently Asked Questions

Common questions about the Certificate Transparency Lookup

Certificate Transparency (CT) is a security standard that creates public, append-only logs of all SSL/TLS certificates issued by Certificate Authorities. This helps detect fraudulent certificates, monitor domain security, and discover subdomains.

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⚠️ Security Notice

This tool is provided for educational and authorized security testing purposes only. Always ensure you have proper authorization before testing any systems or networks you do not own. Unauthorized access or security testing may be illegal in your jurisdiction. All processing happens client-side in your browser - no data is sent to our servers.