# x402 Readiness Checker

> x402 Readiness Checker is a paid API for AI agents from agents.crowdspark.me, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-31).

Probes a paid API URL without paying to verify it correctly implements the x402 payment protocol and reports a readiness score with specific issues.

## Facts

- Endpoint: GET https://agents.crowdspark.me/v1/x402/check?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-readiness-checker-c330fe4d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_6VqfPk9j6-oZg87-ZkRdD

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-readiness-checker-c330fe4d
```

Example prompt: Can you probe https://api.example.com/v1/data and check whether it's properly set up for x402 payments — I want to see the readiness score, any issues, and whether it's ready to list on Bazaar?

## When to prefer this

Use this endpoint whenever you need to verify an API correctly implements the x402 payment protocol before paying it, listing it on a marketplace, or integrating it into an agent workflow. It never actually sends payment, making it safe to run repeatedly. Prefer it over manual inspection when you need a structured score, EIP-55 checksum validation, and Bazaar discovery verification in a single call.

## Known failure modes

- Target URL is unreachable or times out — probe reports connection failure
- Target URL returns non-402 status and is not x402 — x402_detected false, score 0
- payTo address fails EIP-55 checksum — reported as specific issue in issues list
- Missing required fields in 402 response — each missing field listed as a separate issue
- Malformed EIP-712 domain — flagged in issues with details
- Score below 100 with non-empty issues array when implementation is partially compliant

## How this service works

Pay-per-call utilities for AI agents over x402, USDC on Base.

## Output

Returns a JSON object with: the probed URL, probe timing and HTTP status, a boolean ready flag, a 0-100 compliance score, a list of specific issues (or empty if compliant), an accepts array detailing payment requirements (payTo, scheme, network, price_usd, asset_symbol, amount_atomic, max_timeout_seconds), verdict string ('ready' or 'needs_fixes'), x402 version detected, delivery method (header or body), x402_detected boolean, and Bazaar discovery status.

## 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": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "description": "Public http(s) URL of the paid endpoint to probe"
      },
      "method": {
       "enum": [
        "GET",
        "POST"
       ],
       "type": "string",
       "description": "Optional. Default tries GET, then POST if GET returns 404 or 405"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://api.example.com/v1/data",
  "probe": {
   "ms": 312,
   "method": "GET",
   "status": 402,
   "redirects": 0
  },
  "ready": true,
  "score": 100,
  "issues": [],
  "accepts": [
   {
    "pay_to": "0x0dEA0030A17BF886543a757c55924710258c2eec",
    "scheme": "exact",
    "network": "eip155:8453",
    "price_usd": 0.001,
    "asset_symbol": "USDC",
    "amount_atomic": "1000",
    "max_timeout_seconds": 300
   }
  ],
  "verdict": "ready",
  "version": 2,
  "discovery": {
   "bazaar": true
  },
  "delivered_via": "PAYMENT-REQUIRED header",
  "x402_detected": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-readiness-checker-c330fe4d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agents.crowdspark.me](https://www.zero.xyz/host/agents.crowdspark.me/llms.txt)