# x402 Liveness Check

> x402 Liveness Check is a paid API for AI agents from proxy.suverse.io, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-18).

Probes a target x402-protected URL and returns a liveness verdict (ALIVE/DEGRADED/DEAD) plus details about its 402 challenge surface, pricing, networks, and payTo — without sending any payment.

## Facts

- Endpoint: POST https://proxy.suverse.io/v1/data/x402-liveness-check?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-liveness-check-93602033
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IsE3pmGyrFsrQUO7jRSHe

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-liveness-check-93602033 -d '<json body>'
```

Example prompt: Can you probe this x402 resource at https://api.example.com/v1/premium-data to check if it's alive, and tell me what price, network, and payTo address its 402 challenge requires — without actually sending any payment?

## When to prefer this

Use this endpoint when you need to verify that an x402-protected resource is healthy and correctly configured before integrating or paying it, or when you want to inspect its 402 challenge parameters (price, network, payTo) without committing any funds. Prefer this over generic HTTP health checkers when the target uses the x402 payment protocol, as it understands 402 challenge semantics specifically.

## Known failure modes

- SSRF guard blocks private/internal IP targets — returns error if URL resolves to a non-public address
- Target URL is unreachable or times out — returns DEAD verdict with latency data
- Target does not return a 402 response — verdict may be DEGRADED or invalid challenge
- Malformed x402 challenge on target — returns DEAD or DEGRADED with challenge validity flag false
- Auto-refund issued if the check itself fails at the infrastructure level

## How this service works

Probe any x402 resource URL without paying it: ALIVE/DEGRADED/DEAD verdict on its 402 surface - challenge validity, min price, networks, payTo, latency, bazaar extension. SSRF-guarded, no payment ever sent to the target. Auto-refund on failure.

## Output

Returns a structured liveness verdict (ALIVE, DEGRADED, or DEAD) for the target x402 URL, along with details extracted from its 402 challenge: challenge validity, minimum price, accepted payment networks, payTo address, measured latency, and any bazaar extension metadata present. No payment is ever sent to the target.

## 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": {
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "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/x402-liveness-check-93602033/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from proxy.suverse.io](https://www.zero.xyz/host/proxy.suverse.io/llms.txt)