# SiteCheck Web Intel – Certificate Transparency Subdomain Lookup

> SiteCheck Web Intel – Certificate Transparency Subdomain Lookup is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).

Returns subdomain names, wildcard entries, certificate issuers, latest issuance dates, and valid-certificate counts found in Certificate Transparency logs for a given domain via CertSpotter

## Facts

- Endpoint: GET https://api.webintel-api.workers.dev/api/security/crtsh-transparency?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-web-intel-certificate-transparency-subdomain-lookup-fefa2293
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1K74hp-uBELt0eTTKoXhW

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sitecheck-web-intel-certificate-transparency-subdomain-lookup-fefa2293
```

Example prompt: Can you look up all the subdomains and certificate transparency records for stripe.com — I want to see the hostnames, any wildcard certs, who issued them, and which ones are still valid?

## When to prefer this

Choose this endpoint when you need passive, non-intrusive subdomain discovery based on public Certificate Transparency log data — no active scanning, no DNS brute-forcing. It is ideal for security reconnaissance, attack surface mapping, and certificate auditing tasks where stealth and legality matter. Prefer this over active DNS enumeration tools when you need a quick, read-only view of what CAs have publicly disclosed about a domain's certificates.

## Known failure modes

- Missing or invalid 'domain' query parameter returns an error
- Domain not found in CT logs returns an empty result set
- CertSpotter upstream API unavailable causes timeout or 5xx response
- Domains with very large CT log histories are truncated to the first 100 entries with no pagination
- Malformed domain strings may return unexpected results or errors

## How this service works

Subdomain names found in public Certificate Transparency logs for a domain (via CertSpotter): unique host names and wildcard names, issuers, latest issue date and how many listed certificates are still valid. Returns the first page only (up to 100 certificates) and lists at most 100 names; wildcard names are shown as *.domain.

## Output

A list of up to 100 unique hostnames (including wildcard entries like *.domain.com) discovered in Certificate Transparency logs for the queried domain, along with the certificate issuer names, the most recent certificate issuance date per entry, and a count of how many of the listed certificates are currently valid. Only the first page (up to 100 certificates) is returned.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "domain"
     ],
     "properties": {
      "domain": {
       "type": "string",
       "description": "Domain name such as wikipedia.org (required)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-web-intel-certificate-transparency-subdomain-lookup-fefa2293/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.webintel-api.workers.dev](https://www.zero.xyz/host/api.webintel-api.workers.dev/llms.txt)