# QuietSignal x402 Readiness Checker

> QuietSignal x402 Readiness Checker is a paid API for AI agents from 83-29-153-50.sslip.io, paid per call via x402, $0.1/call, status down (last checked 2026-09-15).

Inspects a public URL to verify whether it correctly implements the x402 HTTP payment protocol and is ready for machine discovery

## Facts

- Endpoint: GET https://83-29-153-50.sslip.io/v1/x402-readiness
- Price: $0.1/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quietsignal-x402-readiness-checker-ec9f6d77
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lQb10t_r-I8VzxGNS8HSi

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 quietsignal-x402-readiness-checker-ec9f6d77
```

Example prompt: Check whether https://api.myservice.com/data is properly set up for x402 machine payments — I want to know if it returns a 402 challenge and is ready for agent discovery.

## When to prefer this

Use this endpoint when you need a quick, independent, machine-readable assessment of whether a specific URL correctly implements the x402 HTTP payment protocol — especially before listing an endpoint on a discovery marketplace, debugging a broken x402 integration, or evaluating a third-party endpoint for x402 compatibility. It is not a security audit and only performs bounded public-metadata checks.

## Known failure modes

- Target URL is unreachable or times out — checks may return false or partial results
- Target URL is not a valid URI — input validation error
- Target does not return HTTP 402 at all — target_returns_402 will be false
- OpenAPI spec is not accessible — openapi_reachable will be false
- Payment challenge header/body is missing — target_exposes_payment_challenge will be false
- Payment required ($0.1 USDC via x402) is not satisfied — HTTP 402 returned by this endpoint itself

## How this service works

QuietSignal Public Data: independent, read-only rollup, wallet, opportunity, and developer-data facts for agents, paid per request with USDC over HTTP 402 on Base.

## Output

A JSON object with a schema identifier ('x402-readiness/v1'), three boolean checks (openapi_reachable, target_returns_402, target_exposes_payment_challenge), an overall assessment of whether the endpoint is ready_for_machine_discovery, and a disclaimer noting this is a bounded public-metadata check only, not a security audit.

## 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": "Public x402-enabled endpoint to inspect"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "checks": {
   "openapi_reachable": true,
   "target_returns_402": true,
   "target_exposes_payment_challenge": true
  },
  "schema": "x402-readiness/v1",
  "assessment": {
   "ready_for_machine_discovery": true
  },
  "disclaimer": "Bounded unpaid public-metadata checks only; not a security audit."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quietsignal-x402-readiness-checker-ec9f6d77/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 83-29-153-50.sslip.io](https://www.zero.xyz/host/83-29-153-50.sslip.io/llms.txt)