Free Certificate Transparency Checker & Subdomain Finder
Discover hidden subdomains and monitor SSL certificates through Certificate Transparency logs. Find forgotten infrastructure, detect unauthorized certificate issuance, analyze CT logs, and map your complete attack surface for free.
Subdomain Discovery
Find all subdomains by analyzing Certificate Transparency logs
Certificate Monitoring
Track all SSL certificates issued for your domain and subdomains
CA Analysis
Identify all Certificate Authorities that have issued certificates
Historical Data
View historical certificate issuance and track changes over time
What Certificate Transparency Reveals
Certificate Information
- All SSL certificates issued for your domain
- Certificate issuance timestamps
- Issuing Certificate Authorities (CAs)
- Certificate serial numbers and validity periods
Subdomain Discovery
- Hidden subdomains not in DNS
- Historical subdomains and infrastructure
- Development and staging environments
- Recently added or removed subdomains
Security Insights
- Detect unauthorized certificate issuance
- Identify unusual certificate patterns
- Monitor for rogue or wildcard certificates
- Track certificate authority changes
Attack Surface Analysis
- Map your entire domain infrastructure
- Discover forgotten or abandoned subdomains
- Identify potential security exposure
- Audit your certificate management
About Certificate Transparency
Certificate Transparency (CT) is an internet security standard that provides an open framework for monitoring and auditing SSL/TLS certificates. Every publicly trusted certificate is logged in append-only CT logs that anyone can query.
CT logs are invaluable for:
- Subdomain Discovery: Find all subdomains by searching CT logs for certificates
- Security Monitoring: Detect unauthorized or suspicious certificate issuance
- Certificate Management: Track all certificates across your infrastructure
- Compliance: Audit certificate issuance for regulatory compliance
- Threat Intelligence: Identify potential phishing domains targeting your brand
Common Use Cases
Security Teams
- Monitor for unauthorized certificates
- Discover shadow IT infrastructure
- Detect phishing attempts using similar domains
- Audit certificate authority selection
Bug Bounty Hunters
- Find hidden subdomains for testing
- Discover development/staging servers
- Identify forgotten infrastructure
- Map the complete attack surface
DevOps Teams
- Track certificate lifecycle
- Identify expiring certificates
- Audit infrastructure inventory
- Monitor certificate deployment
Want the Complete Picture?
FREEThis Certificate Transparency Check is great for a quick check, but our Full Security Scan gives you a comprehensive security audit in one go.