# Would Pay Again – Book Classified Ad #4

> Would Pay Again – Book Classified Ad #4 is a paid API for AI agents from wouldpayagain.com, paid per call via x402, $0.7/call, status unknown (last checked 2026-10-29).

Books a classified advertisement slot (slot #4) in the Would Pay Again newsletter about machine payments, paying $0.70 USDC via x402 on Base.

## Facts

- Endpoint: POST https://wouldpayagain.com/api/ads/book/classified-4?utm_source=zero.xyz
- Price: $0.7/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/would-pay-again-book-classified-ad-4-2a6e5d51
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_UFPgcRdGVyDNWI8HgVgRw

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 would-pay-again-book-classified-ad-4-2a6e5d51 -d '<json body>'
```

Example prompt: Book a classified ad in the Would Pay Again newsletter — it's about the x402 machine-payments economy — pay the $0.70 USDC fee and submit my ad body as JSON so I can get back the booking ID and tearsheet link.

## When to prefer this

Use this endpoint when an agent needs to purchase a specific classified advertising slot (#4) in the Would Pay Again newsletter targeting the x402 and machine-payments crypto audience, and can pay $0.70 USDC via the x402 protocol on Base. Prefer this over generic ad networks when the goal is reaching developers and early adopters specifically interested in machine payments, autonomous agent commerce, or USDC/Base ecosystem products.

## Known failure modes

- Payment failure: insufficient USDC balance or x402 payment not accepted — booking not created
- Invalid body: missing required fields (type, method, bodyType, body) returns validation error
- Slot unavailable: classified slot #4 may already be booked for the target issue
- Network error: Base blockchain congestion causing settlement_tx delay or timeout
- Malformed request: wrong bodyType enum value or unsupported HTTP method causes rejection

## How this service works

A newsletter about the x402 machine-payments economy, sold over x402 itself. USDC on Base.

## Output

Returns a JSON object confirming the booking with: a boolean 'ok' field, a 'status' of 'pending_review', a 'confirmed' boolean, a 'tearsheet' URL for reviewing the ad placement, a numeric 'booking_id', and the on-chain 'settlement_tx' hash from the USDC payment 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object"
    },
    "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": {}
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "status": "pending_review",
  "confirmed": true,
  "tearsheet": "https://wouldpayagain.com/api/ads/booking/6",
  "booking_id": 6,
  "settlement_tx": "0x…"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/would-pay-again-book-classified-ad-4-2a6e5d51/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from wouldpayagain.com](https://www.zero.xyz/host/wouldpayagain.com/llms.txt)