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DNS Subdomain Enumeration via Certificate Transparency
x402
DNS Subdomain Enumeration via Certificate Transparency is a paid API for AI agents from dns-intel-api-production.up.railway.app, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).
Discovers all known subdomains for an apex domain by querying Certificate Transparency logs (crt.sh), returning a de-duplicated, sorted list of up to 1000 results.
Price / call$0.002
Success—
StatusUnknown
How this service works
Discover subdomains for a domain via Certificate Transparency logs (crt.sh); returns a de-duplicated, sorted list.
Output
A de-duplicated, sorted list of subdomain strings discovered from Certificate Transparency log entries for the requested apex domain, capped at the requested limit (default 200, max 1000).
Example use cases
Security audit of company attack surface
“I need to map the full subdomain footprint of acmecorp.com for a security assessment — can you pull all known subdomains from certificate transparency logs, up to 1000?”
Competitor infrastructure research
“What subdomains does shopify.com have exposed in certificate transparency logs? Give me up to 300 results so I can understand their infrastructure layout.”
Pre-pentest passive recon
“Before I start a penetration test on targetdomain.com, can you do passive subdomain discovery using CT logs and return everything you find, up to 500 subdomains?”
Technical details
Endpoint
POSThttps://dns-intel-api-production.up.railway.app/dns/subdomainsWhen to prefer
Use this endpoint when you need passive, non-intrusive subdomain discovery without sending traffic directly to the target — ideal for reconnaissance, attack surface mapping, or security audits. Prefer it over active DNS brute-forcing when stealth matters or when you want a quick snapshot of publicly issued certificates. It complements sibling endpoints (WHOIS, DNS resolution, TLS cert details) for comprehensive domain intelligence.
Side effects
- Invalid or non-existent domain returns empty list or error
- crt.sh upstream unavailability causes timeout or 502
- Limit parameter out of range (below 1 or above 1000) returns validation error
- Very new domains with no CT log entries return empty results
- Rate limiting from crt.sh may cause partial results or failure
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| limit | integer | Maximum number of subdomains to return. Defaults to 200. |
| domain | string | Apex domain to enumerate subdomains for via Certificate Transparency logs, e.g. 'example.com'. |
Tags
x402
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