# quartermaster.surewhynot.app x402 Payment Pre-flight Simulator

> quartermaster.surewhynot.app x402 Payment Pre-flight Simulator is a paid API for AI agents from quartermaster.surewhynot.app, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).

Decodes an x402 payment challenge for a given endpoint, reports costs across Base and Solana rails, identifies the cheapest option, and optionally verifies a wallet's affordability on Base.

## Facts

- Endpoint: GET https://quartermaster.surewhynot.app/v1/x402/simulate
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quartermaster-surewhynot-app-x402-payment-pre-flight-simulator-90743190
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_x1zJ98mlCEWkSBePtGUQq

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 quartermaster-surewhynot-app-x402-payment-pre-flight-simulator-90743190
```

Example prompt: Before I actually pay, can you simulate the x402 payment for https://some-api.example.com/data and tell me which rail is cheapest — also check if my wallet 0xAbC1234567890AbC1234567890AbC1234567890Ab can afford it on Base?

## When to prefer this

Use this endpoint when you need to inspect or compare x402 payment costs before committing to a payment, especially when you want to choose between Base and Solana rails for cost efficiency, or when you need to programmatically verify that a specific wallet can afford a call before executing it. Prefer this over the deep audit endpoint when you only need cost and affordability data, not a full compliance audit.

## Known failure modes

- Target URL is not an x402-protected endpoint — returns error indicating no payment challenge found
- Invalid or non-EVM wallet address format — validation error on address field
- Target endpoint is unreachable or returns unexpected status — upstream fetch error
- Wallet balance check fails due to RPC issues on Base — affordability result unavailable

## How this service works

Pre-flight an x402 payment: decode the endpoint's challenge, report the cost on every rail (Base and Solana) and the cheapest, and — with a payer address — verify the wallet can afford the call on Base.

## Output

Returns a decoded breakdown of the x402 payment challenge for the target endpoint, including per-rail costs for Base and Solana, which rail is cheapest, and — if a payer address was supplied — whether that wallet holds sufficient funds to cover the call on Base.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "format": "uri",
       "description": "The x402 endpoint to pre-flight"
      },
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "Optional payer wallet to check Base affordability"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quartermaster-surewhynot-app-x402-payment-pre-flight-simulator-90743190/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from quartermaster.surewhynot.app](https://www.zero.xyz/host/quartermaster.surewhynot.app/llms.txt)