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Subdomain Discovery via Certificate Database
x402
Subdomain Discovery via Certificate Database is a paid API for AI agents from domain.hugen.tokyo, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).
Finds all subdomains of a domain that have issued SSL certificates, with deduplication and wildcard handling
Price / call$0.01
Success—
StatusUnknown
How this service works
Subdomain discovery via certificate database — finds all subdomains with issued SSL certificates. Discovers API endpoints, staging servers, mail servers, and forgotten infrastructure. Deduplication and wildcard handling included. Accepts USDC payments on Base and Solana
Output
A deduplicated list of subdomains discovered via SSL certificate database records, including handling for wildcard certificates. Each entry represents a hostname that has had an SSL certificate issued, potentially revealing API endpoints, staging environments, mail servers, and forgotten infrastructure associated with the queried domain.
Example use cases
Example prompt
“Can you find all the subdomains for stripe.com using certificate transparency logs? I want to see their API endpoints, staging servers, and any other infrastructure they've exposed.”
Technical details
Endpoint
GEThttps://domain.hugen.tokyo/domain/subdomainsWhen to prefer
Use this endpoint when you need passive, non-intrusive subdomain discovery using certificate transparency logs rather than active DNS brute-forcing. It is particularly useful for security assessments, competitive intelligence, attack surface mapping, and finding forgotten or undocumented infrastructure without sending traffic to the target. Preferred over DNS brute-force tools when stealth or completeness via CT logs is desired.
Side effects
- Domain not found or no certificates issued — returns empty list
- Invalid domain format — returns 400 error
- Rate limiting or payment failure — returns 402/429 error
- Certificate database lookup timeout — may return partial results
Input
{
"domain": "example.com"
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| input | — |
Output
{
"domain": "example.com",
"source": "crt.sh (Certificate Transparency)",
"subdomains": [
"dev.example.com",
"example.com",
"m.example.com",
"products.example.com",
"support.example.com",
"www.example.com"
],
"subdomain_count": 6
}Tags
x402
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