# 402utils.com x402 Parametric Payment Test Endpoint

> 402utils.com x402 Parametric Payment Test Endpoint is a paid API for AI agents from 402utils.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).

Serves as a configurable x402 payment-test endpoint where the required payment amount is set via ?amount= (clamped $0.001–$0.05 USD), returning a confirmation object after successful USDC payment

## Facts

- Endpoint: GET https://402utils.com/v1/donate
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/402utils-com-x402-parametric-payment-test-endpoint-94545d0d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IGONcGhVP_8K2mVrHzXVx

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 402utils-com-x402-parametric-payment-test-endpoint-94545d0d
```

Example prompt: Run an x402 payment test against the 402utils donate endpoint with an amount of $0.013 and note it as 'integration-test-run-42' so I can verify my client pays exactly that amount and the on-chain USDC tx matches.

## When to prefer this

Use this endpoint when you need a deterministic, parametric x402 payment test target — one where you control the exact required price and can assert that your client both responds correctly to a 402 and settles the precise on-chain USDC amount. It is purpose-built for integration testing x402 client implementations, unlike real services where the price is fixed and not configurable.

## Known failure modes

- Payment not submitted — endpoint returns HTTP 402 with the exact required amount in the WWW-Authenticate header so the client knows what to pay
- Amount clamped — if ?amount is outside $0.001–$0.05, it is silently clamped and clamped:true is returned in the response
- Invalid or missing ?amount — defaults to $0.01 with no error; clamped field absent
- On-chain USDC transaction mismatch — payment rejected if the settled amount does not match the demanded amount
- Network or facilitator timeout — payment may not settle, resulting in a failed retry

## How this service works

Support 402utils — or use it as a parametric x402 payment-test endpoint: you set the price with ?amount= (USD, clamped to $0.001–$0.05) and the 402 demands exactly that, so you can assert a client pays the precise amount and the on-chain USDC tx matches. After payment returns {thanks, amount, message}. The amount is a pure function of ?amount, identical on the unpaid probe and the paid retry.

## Output

After successful USDC payment, returns a JSON object with: thanks (true), amount (USD actually charged, matching the settled on-chain tx), currency ('USD'), message (string), and optionally clamped (true if the requested amount was out of range), requested (the raw ?amount sent), and note (your ?note echoed back for correlation).

## 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",
     "properties": {
      "note": {
       "type": "string",
       "description": "Optional free-text note echoed back (handy to correlate a payment-test run)."
      },
      "amount": {
       "type": "string",
       "description": "Amount to pay in USD, e.g. 0.013. Clamped to $0.001–$0.05. Omitted/invalid → $0.01."
      }
     },
     "description": "Query string only."
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "thanks",
      "amount",
      "currency",
      "message"
     ],
     "properties": {
      "note": {
       "type": "string",
       "description": "Your ?note, echoed (present only when provided)."
      },
      "amount": {
       "type": "number",
       "description": "USD amount actually charged (matches the settled tx)."
      },
      "thanks": {
       "type": "boolean",
       "const": true
      },
      "clamped": {
       "type": "boolean",
       "description": "True when the requested amount fell outside $0.001–$0.05 and was pulled into the band."
      },
      "message": {
       "type": "string"
      },
      "currency": {
       "type": "string",
       "const": "USD"
      },
      "requested": {
       "type": "string",
       "description": "The raw ?amount you sent (present only when clamped)."
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "amount": 0.013,
  "thanks": true,
  "message": "Thank you for supporting 402utils.",
  "currency": "USD"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/402utils-com-x402-parametric-payment-test-endpoint-94545d0d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 402utils.com](https://www.zero.xyz/host/402utils.com/llms.txt)