# x402 Payment Challenge Sanity Checker

> x402 Payment Challenge Sanity Checker is a paid API for AI agents from www.mahastrategies.com, paid per call via x402, $0.0035/call, status unknown (last checked 2026-10-16).

Validates the structure and policy fields of an x402-v2 exact-payment challenge against caller-supplied expected values for URL, EVM network, asset, payee, and maximum price — without making live requests or payments.

## Facts

- Endpoint: POST https://www.mahastrategies.com/api/v1/micro/x402-challenge-sanity?utm_source=zero.xyz
- Price: $0.0035/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-payment-challenge-sanity-checker-1f396025
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_C7hbpUGRG7afw6XuGK3dh

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-payment-challenge-sanity-checker-1f396025 -d '<json body>'
```

Example prompt: Can you sanity-check this x402-v2 payment challenge to make sure the payee, CAIP-2 network, asset, and price all match what I expect before I authorize anything — no live payment, just a structural check?

## When to prefer this

Use this endpoint when you need a fast, offline structural check of an x402-v2 payment challenge before authorizing payment — particularly when you want to verify payee, network, asset, and price policy fields match your expectations without incurring any live network request, payment, or facilitator lookup. Prefer this over manual parsing when building agents that must validate x402 headers programmatically and need an auditable digest trail.

## Known failure modes

- Missing required fields in challenge or expected object returns a validation error
- Mismatched URL, payee, network, or asset causes boundary violations in the result
- Malformed CAIP-2 network identifier may cause parsing failure
- Invalid or non-HTTPS resource URL rejected at structure check
- Schema mismatch (wrong bodyType or method) returns HTTP-level error
- dataClass enum value outside 'public' or 'synthetic' causes rejection

## How this service works

Inspect one supplied x402-v2 exact-payment challenge against an explicit expected HTTPS resource, EVM CAIP-2 network, asset, payee and maximum price. Checks both URL declarations, structure and payment-policy fields only; no live probe, payment, facilitator verification or server-authenticity claim.

## Output

Returns a structured result object containing a pass/fail validation outcome, a list of boundary violations (if any), the offer ID ('x402-challenge-sanity'), input and receipt digests for audit purposes, and the amount in base units (3500). No live network probe, payment, or facilitator verification is performed.

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "dataClass",
      "expected",
      "challenge"
     ],
     "properties": {
      "expected": {
       "type": "object"
      },
      "challenge": {
       "type": "object"
      },
      "dataClass": {
       "enum": [
        "public",
        "synthetic"
       ],
       "type": "string"
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "version",
      "offerId",
      "amountBaseUnits",
      "inputDigest",
      "result",
      "boundaries",
      "receiptDigest"
     ],
     "properties": {
      "result": {
       "type": "object"
      },
      "offerId": {
       "enum": [
        "x402-challenge-sanity"
       ],
       "type": "string"
      },
      "version": {
       "enum": [
        "maha-microproducts/0.1"
       ],
       "type": "string"
      },
      "boundaries": {
       "type": "array",
       "maxItems": 128,
       "minItems": 0
      },
      "inputDigest": {
       "type": "string",
       "maxLength": 71
      },
      "receiptDigest": {
       "type": "string",
       "maxLength": 71
      },
      "amountBaseUnits": {
       "enum": [
        "3500"
       ],
       "type": "string"
      }
     },
     "additionalProperties": false
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-payment-challenge-sanity-checker-1f396025/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from www.mahastrategies.com](https://www.zero.xyz/host/www.mahastrategies.com/llms.txt)