# Maxwell x402 Endpoint Inspector

> Maxwell x402 Endpoint Inspector is a paid API for AI agents from api.maxwellinternational.ai, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-02).

Checks a single HTTP(S) URL for a valid x402 payment challenge, reports its USDC price relative to category peers, lists payTo wallets with 30-day USDC received, and shows probe-based uptime history — without making a payment.

## Facts

- Endpoint: GET https://api.maxwellinternational.ai/v1/x402/endpoint/check?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/maxwell-x402-endpoint-inspector-6c2b4ccd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_tG_1kndSe0Zbw-9wAvjkT

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 maxwell-x402-endpoint-inspector-6c2b4ccd
```

Example prompt: Can you check whether https://api.example.com/premium-data is a valid x402 endpoint using a GET request — I want to know its USDC price, how it compares to similar endpoints, which wallets it pays out to and how much they've received in the last 30 days, and whether it's been reliably up?

## When to prefer this

Use this endpoint when you need a factual, no-payment inspection of a specific x402 URL — especially to verify protocol compliance, compare pricing to peers, trace payout wallets, or audit uptime history before deciding whether to pay. Prefer this over generic HTTP probers when x402-specific signals (price, wallet, category median, probe history) are needed. Not a safety verdict tool; use it for due diligence and discovery.

## Known failure modes

- URL does not return a 402 response (not an x402 endpoint)
- x402 challenge is malformed or missing required fields (problems array populated)
- Wallet payment history not available if not collected by Maxwell's collector
- Uptime history absent for newly discovered endpoints
- Network timeout if the target URL is unreachable
- Invalid HTTP method supplied (must be GET, HEAD, or DELETE)
- Input URL uses an unsupported scheme (not http or https)

## How this service works

Checks one http(s) URL without paying it: whether it returns a valid x402 payment challenge, its USDC price against the median of its category, the payTo wallets and their USDC received in the last 30 days where our collector has them, and our own probe history (uptime since first seen). Signals with sources; a factual report, not a safety verdict.

## Output

A structured report including: whether the URL returns a valid x402 402 payment challenge (state and any problems), the endpoint's USDC price and how it compares to the median for its category, known payTo wallet addresses and the USDC each has received in the last 30 days (where collected), and the probe/uptime history since the endpoint was first seen. All signals are sourced; no safety verdict is issued.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://www.x402scan.com/api/x402/resources",
  "paywall": {
   "state": "ok_402",
   "problems": []
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/maxwell-x402-endpoint-inspector-6c2b4ccd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.maxwellinternational.ai](https://www.zero.xyz/host/api.maxwellinternational.ai/llms.txt)