# Vextorium Subdomain Discovery via Certificate Transparency

> Vextorium Subdomain Discovery via Certificate Transparency is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-20).

Returns all subdomains of a given domain found in public Certificate Transparency logs, including subdomain names, wildcard count, and certificate dates.

## Facts

- Endpoint: POST https://api.vextorium.com/subdominios-pago?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vextorium-subdomain-discovery-via-certificate-transparency-9f0f7ac0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_TUrTXsXzXtXMrN5_gredu

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-discovery-via-certificate-transparency-9f0f7ac0 -d '<json body>'
```

Example prompt: Can you look up all subdomains of example.com that have appeared in Certificate Transparency logs? Limit the results to 50 subdomains.

## When to prefer this

Use this endpoint when you need passive, non-intrusive subdomain discovery sourced from public Certificate Transparency logs without sending any traffic to the target domain. It is ideal for OSINT, asset inventory, and security audits where stealth or comprehensiveness of historical data matters. Prefer this over active DNS brute-forcing tools when you want a purely passive approach or need certificate issuance dates alongside subdomain names.

## Known failure modes

- Domain not found in CT logs — returns empty subdomain list with zero counts
- Invalid or malformed domain input — likely returns an error or empty result
- Rate limiting — too many requests may result in errors
- Limit parameter ignored or capped at a server-side maximum
- Very new domains with no issued certificates return no results

## How this service works

Subdomains of a domain found in public Certificate Transparency logs (every TLS certificate issued): names, wildcard count and certificate dates. For asset inventory, audits and OSINT.

## Output

Returns a JSON object containing the queried domain, a list of subdomain objects (each with name and latest certificate date), the total subdomain count, wildcard count, the date of the first certificate ever seen, the number of certificates analyzed, and the data source. May include a note field with additional context.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "limite": {
   "type": "integer"
  },
  "dominio": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vextorium-subdomain-discovery-via-certificate-transparency-9f0f7ac0/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)