# Vextorium Subdomain Lookup

> Vextorium Subdomain Lookup is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-28).

Discovers subdomains and wildcard entries for a given domain using Certificate Transparency logs via SSLMate CertSpotter

## Facts

- Endpoint: POST https://api.vextorium.com/v1/subdomains?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vextorium-subdomain-lookup-78613631
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ORYjsMqN_rW6BYUQAJrTt

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 vextorium-subdomain-lookup-78613631 -d '<json body>'
```

Example prompt: Can you find all the subdomains for example.com using certificate transparency logs, and return up to 50 results?

## When to prefer this

Use this endpoint when you need to discover subdomains passively using certificate transparency logs without active DNS scanning. It's ideal for OSINT, security auditing, and infrastructure reconnaissance where you want historical SSL certificate data. Prefer this over active DNS enumeration tools when stealth or a read-only approach is required.

## Known failure modes

- Domain not found in certificate transparency logs — returns empty subdomains array
- Invalid domain format — may return error or empty result
- Rate limiting or payment failure — request rejected before processing
- Domain has no SSL certificates — returns zero results
- Limit parameter too large — may be silently capped

## How this service works

558 pay-per-call data APIs for AI agents: Solana and EVM on-chain data, tokenized stocks, DeFi, Hyperliquid, economy and official statistics, FX, validation, web and developer tools. Pay in USDC via x402.

## Output

A JSON object containing the queried domain, total number of subdomains found, a list of subdomain objects with their names and last certificate dates, the date of the first certificate ever seen, the number of certificates analyzed, wildcard count, and the data source (Certificate Transparency via SSLMate CertSpotter), plus a note about API history limits.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "limit": {
   "type": "integer"
  },
  "domain": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "note": "Only recent valid certificates; the free API limits history.",
  "total": 2,
  "domain": "vextorium.com",
  "source": "Certificate Transparency via SSLMate CertSpotter",
  "wildcards": 1,
  "subdomains": [
   {
    "name": "*.vextorium.com",
    "last_certificate": "2026-10-02T00:00:00Z"
   },
   {
    "name": "vextorium.com",
    "last_certificate": "2026-10-02T00:00:00Z"
   }
  ],
  "first_certificate": "2026-09-27T12:11:54Z",
  "analyzed_certificates": 4
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vextorium-subdomain-lookup-78613631/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)