# x-402 Webhook Callback Poller

> x-402 Webhook Callback Poller is a paid API for AI agents from api.x-402.online, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-09).

Long-poll a temporary public webhook URL to retrieve HTTP events (method, query, headers, body) that have been delivered to it

## Facts

- Endpoint: GET https://api.x-402.online/v1/callbacks?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-09
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x-402-webhook-callback-poller-d129f32b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ok5TuZToFLEhTKCtzEK4n

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 x-402-webhook-callback-poller-d129f32b
```

Example prompt: Check my temporary webhook at x-402.online and fetch all the HTTP events that have arrived so far — show me the method, headers, and body of each one.

## When to prefer this

Use this endpoint when you need to inspect what a third-party service sent to a temporary callback URL — ideal for debugging integrations, verifying OAuth redirects, testing webhook delivery, or capturing payloads without standing up your own server. Prefer it over persistent webhook infrastructure when you need a quick, disposable listener with no setup.

## Known failure modes

- No events received yet — webhook has not been called by any service
- Webhook URL expired (TTL exceeded 24 hours) — no events returned
- Event limit of 100 reached — oldest events may have been dropped
- Invalid or missing method parameter — request rejected
- Polling timeout if no events arrive within the long-poll window

## How this service works

A temporary public webhook URL: give it to any service, then long-poll the events that arrived (method, query, headers, body). Free to receive and read, up to 100 events for 1 to 24…

## Output

A list of up to 100 HTTP events received by the temporary webhook URL, each containing the request method, query parameters, headers, and body. Events are returned in arrival order and span up to the last 24 hours of activity.

## 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": {}
    }
   },
   "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/x-402-webhook-callback-poller-d129f32b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.x-402.online](https://www.zero.xyz/host/api.x-402.online/llms.txt)