Censys
An internet asset intelligence search engine to discover and analyze global infrastructure
🔍 What is Censys?
Censys is a search engine specialized in internet asset intelligence. It continuously scans the internet to index servers, certificates and exposed services, giving a complete view of global infrastructure.
4 billion
IP addresses scanned
Daily
Data updates
API REST
Easy integration
Key features
Explore Censys's advanced capabilities for infrastructure research
Infrastructure search
Discover exposed servers, services and certificates
Certificate intelligence
Analyze SSL/TLS certificates and their owners
Banner search
Identify services by their HTTP/FTP/SSH banners
Geolocation
Geolocate the assets you discover
Monitoring over time
Track infrastructure changes over time
API REST
Integrate Censys into your tools and workflows
Search types
Master the different search types to get more out of your investigations
Hosts
Host and server search
services.service_name: SSHExposed SSH servers
location.country: FRAssets in France
services.port: 443HTTPS servers
autonomous_system.name: "OVH"Infrastructure OVH
Certificates
SSL/TLS certificate search
names: "*.example.com"Certificates for example.com
parsed.issuer.organization: "Let's Encrypt"Let's Encrypt certificates
validation_level: DVDomain Validated certificates
parsed.validity_period.not_after: [2026-01-01 TO 2026-12-31]Certificates expiring in 2024
Practical use cases
See how to use Censys in your investigations
Infrastructure reconnaissance
Discover an organization's exposed infrastructure
Investigation steps:
- 1Search by domain name
- 2Identify subdomains
- 3Analyze SSL certificates
- 4Map exposed services
Example query:
names: "*.target.com"Vulnerability search
Identify exposed vulnerable services
Investigation steps:
- 1Search by service version
- 2Filter by known vulnerabilities
- 3Geographic analysis
- 4Target prioritization
Example query:
services.software.product: "Apache" AND services.software.version: "2.4.29"Brand monitoring
Monitor how your brand is used in certificates
Investigation steps:
- 1Search by brand name
- 2Analyze suspicious certificates
- 3Identify fraudulent domains
- 4Automated alerts
Example query:
names: "*mycompany*" AND NOT names: "*.mycompany.com"API Censys
Integrate Censys into your automation workflows
Authentication
curl -u "API_ID:API_SECRET" "https://search.censys.io/api/v2/hosts/search"Search example
{
"q": "services.service_name: SSH",
"per_page": 50,
"cursor": ""
}Best practices
Optimizing searches
- • Use specific filters to narrow results
- • Combine several criteria with AND/OR
- • Use wildcards (*) sparingly
- • Use structured fields for more precision
Using the API
- • Respect the API rate limits
- • Implement robust error handling
- • Use pagination for large volumes
- • Cache results to avoid redundant requests
Analyzing results
- • Check how fresh the data is
- • Cross-check information with other sources
- • Analyze trends over time
- • Document your important findings
⚠️ Legal and ethical considerations
- • Respect Censys's terms of use
- • Never use the data for malicious purposes
- • Check your rights before analyzing infrastructure
- • Protect any sensitive information you find
- • Report vulnerabilities responsibly
Start your asset intelligence
Create a Censys account and start exploring the world's internet infrastructure.
Ready to put it into practice?
CyberXTEL is our free platform to train hands-on: certifications, CTFs and a dedicated cyber awareness space.