# SiteCheck SSL Certificate Transparency Lookup

> SiteCheck SSL Certificate Transparency Lookup is a paid API for AI agents from api.sitecheck-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-28).

Retrieves SSL/TLS certificate issuances for a domain from Certificate Transparency logs, including current certificates, subdomains, and expiry info

## Facts

- Endpoint: GET https://api.sitecheck-api.workers.dev/api/certs?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-28
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-ssl-certificate-transparency-lookup-567d58d3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_g_4HjDsB1SD-w1ZYYtOcy

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-ssl-certificate-transparency-lookup-567d58d3
```

Example prompt: Pull up all the SSL certificates issued for stripe.com from certificate transparency logs — I want to see who issued them, which subdomains are covered, and how many days are left before they expire.

## When to prefer this

Use this endpoint when you need to audit SSL/TLS certificate history and coverage for a domain, discover subdomains via CT logs (a passive recon technique), check certificate expiry dates, or detect unexpected/rogue certificates issued by unauthorized CAs. Prefer this over DNS enumeration tools when you want certificate-sourced subdomain discovery without active scanning.

## Known failure modes

- Invalid or non-existent domain returns an error or empty result
- Domain with no certificate transparency entries returns empty issuances array
- CertSpotter API upstream unavailability may cause timeout or error
- Rate limiting on upstream CT log provider may delay response
- Truncated subdomain list if domain has very large number of issuances

## How this service works

Current TLS certificates for a domain from Certificate Transparency logs (via CertSpotter): issuer, validity dates and days left, DNS names (up to 100 per certificate), and the distinct subdomains seen. Keyless tier: one request per call; answers are cached an hour.

## Output

Returns a JSON object containing the domain queried, a list of current active certificates (each with issuer, DNS names covered, notBefore, notAfter, and daysLeft), a full list of discovered subdomains, total issuance count, the data source attribution (CertSpotter), and a checkedAt timestamp.

## 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, e.g. example.com"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "domain": "cloudflare.com",
  "source": "https://api.certspotter.com/v1/issuances (Certificate Transparency logs)",
  "current": [
   {
    "issuer": "SSL.com",
    "daysLeft": 136,
    "dnsNames": [
     "staging.cp12.cloudflare.com"
    ],
    "notAfter": "2027-02-27T18:53:54Z",
    "notBefore": "2026-02-27T18:53:54Z"
   },
   {
    "issuer": "SSL.com",
    "daysLeft": 136,
    "dnsNames": [
     "cp12.cloudflare.com"
    ],
    "notAfter": "2027-02-27T18:53:58Z",
    "notBefore": "2026-02-27T18:53:58Z"
   },
   {
    "issuer": "SSL.com",
    "daysLeft": 126,
    "dnsNames": [
     "time.cloudflare.com",
     "www.time.cloudflare.com"
    ],
    "notAfter": "2027-02-17T21:30:57Z",
    "notBefore": "2026-02-17T21:30:57Z"
   }
  ],
  "checkedAt": "2026-10-14T07:00:57.376Z",
  "issuances": 100,
  "subdomains": [
   "accounts-test.staging.realtime.cloudflare.com",
   "accounts.staging.realtime.cloudflare.com",
   "ai.cloudflare.com"
  ],
  "attribution": "Certificate Transparency logs via CertSpotter"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-ssl-certificate-transparency-lookup-567d58d3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.sitecheck-api.workers.dev](https://www.zero.xyz/host/api.sitecheck-api.workers.dev/llms.txt)