# x402 Agent Services – SSL Certificate Checker

> x402 Agent Services – SSL Certificate Checker is a paid API for AI agents from call402.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-30).

Checks the TLS/SSL certificate status of a given domain, returning expiry, issuer, chain validity, fingerprint, and SANs

## Facts

- Endpoint: POST https://call402.com/api/ssl-check?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-agent-services-ssl-certificate-checker-60874280
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__tNHxT7hH5Rrb9C7fhXcC

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 x402-agent-services-ssl-certificate-checker-60874280 -d '<json body>'
```

Example prompt: Can you check the SSL certificate for api.mycompany.com — I want to know if it's valid, who issued it, and how many days are left before it expires?

## When to prefer this

Use this endpoint when you need programmatic, real-time TLS certificate inspection for a specific domain — especially in agent workflows monitoring certificate expiry, validating HTTPS configuration before deployments, or diagnosing SSL errors. Prefer this over manual browser inspection or cert-monitoring SaaS dashboards when you need machine-readable certificate metadata on demand at low cost.

## Known failure modes

- Domain does not exist or is unreachable — connection timeout or DNS failure
- Port is not open or not serving TLS — connection refused
- Certificate chain verification fails — chain_verified returns false
- Invalid host format in request body — validation error
- Payment not included — HTTP 402 returned with payment requirements before any check is performed

## How this service works

USDC pay-per-call APIs for AI agents via the x402 protocol (v2, exact, Base mainnet). Send a request, receive HTTP 402 with payment requirements, pay with @x402/fetch or any x402 client, retry with the PAYMENT-SIGNATURE header.

## Output

Returns a JSON object with the domain's TLS certificate details: issuer (O and CN), subject CN, validity window (valid_from / valid_to), days remaining, expiry status (expired boolean), chain verification result, SHA-256 fingerprint, serial number, port used, and list of subject alt names (SANs). Also includes a meta field indicating the data source (direct TLS handshake).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "host": {
   "type": "string",
   "description": "Domain name, optionally host:port (default port 443)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "host": "example.com",
  "meta": {
   "source": "direct TLS handshake (first-party)"
  },
  "port": 443,
  "issuer": {
   "O": "Let's Encrypt",
   "CN": "R13"
  },
  "expired": false,
  "subject": {
   "CN": "example.com"
  },
  "valid_to": "Nov 30 00:00:00 2026 GMT",
  "valid_from": "Sep  1 00:00:00 2026 GMT",
  "serial_number": "03AB...",
  "chain_verified": true,
  "days_remaining": 40,
  "fingerprint256": "AA:BB:...",
  "subject_alt_names": [
   "example.com",
   "www.example.com"
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-agent-services-ssl-certificate-checker-60874280/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from call402.com](https://www.zero.xyz/host/call402.com/llms.txt)