# ASIN402 Amazon ASIN Price & Stock Watcher

> ASIN402 Amazon ASIN Price & Stock Watcher is a paid API for AI agents from asin402.com, paid per call via x402, $0.168/call, status unknown (last checked 2026-10-31).

Sets up a scheduled monitoring job that checks 1-50 Amazon ASINs for price, buy box, and stock changes at a configured interval, returning a watch key to poll for change events.

## Facts

- Endpoint: GET https://asin402.com/api/watch?utm_source=zero.xyz
- Price: $0.168/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/asin402-amazon-asin-price-stock-watcher-2940eca4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zrF_TmQq0SYkVDbeQfbX4

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 asin402-amazon-asin-price-stock-watcher-2940eca4
```

Example prompt: Watch ASINs B09G9HD6PD and 0735211299 on the US Amazon marketplace every 6 hours for 7 days, track the buy box, and fire an event if the price drops below $18.

## When to prefer this

Choose this endpoint when you need ongoing, scheduled surveillance of Amazon product prices, stock, and buy box changes over days or weeks rather than a one-time snapshot. It is ideal when you want change-event alerts (price drop, out of stock, buy box seller change, below target price) across 1-50 ASINs with configurable frequency (1h to 24h). Prefer it over one-time price lookup endpoints when you need historical change logging or automated deal detection without building your own polling infrastructure.

## Known failure modes

- Invalid or non-existent ASINs return no data for those items
- More than 50 ASINs in a single call rejected
- Unsupported marketplace code returns error
- Interval or days value outside allowed range returns validation error
- Payment failure via x402 protocol halts watch creation
- Status URL must be polled manually — no push/webhook delivery

## How this service works

Watch Amazon ASINs: scheduled price, buy box and stock checks with change alerts. Pay once to monitor 1-50 ASINs every 1h, 3h, 6h, 12h or 24h for 1-30 days. Each check records buy box, Amazon, lowest new/used price, stock, buy box seller, offer count, sales rank and rating, and logs changes as events (price drops/rises, out of stock, back in stock, buy box seller change, below your target price). Poll the free status URL with your watch key to read new events. The first check runs immediately. P

## Output

Returns a JSON object containing a watch_id, a free status_url to poll for events, a watch key, the number of checks planned, the next check timestamp, the marketplace, interval, days, price paid, and the current snapshot of all tracked ASINs (buy box price, Amazon price, lowest new/used prices, stock status, offer count, sales rank). Change events (price drops/rises, stock changes, buy box seller changes, target price breaches) are logged and available via polling the status URL.

## 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": [
      "asins"
     ],
     "properties": {
      "days": {
       "type": "integer",
       "description": "How long to watch, 1-30 days. Default 7"
      },
      "asins": {
       "type": "string",
       "description": "1-50 comma-separated ASINs (or an array in a POST body)"
      },
      "buybox": {
       "enum": [
        0,
        1
       ],
       "type": "integer",
       "description": "1 (default) tracks buy box price and seller. 0 = cheaper: Amazon and lowest offer prices only"
      },
      "domain": {
       "type": "string",
       "description": "Marketplace: us, uk, de, fr, jp, ca, it, es, in, mx, br. Default us"
      },
      "interval": {
       "enum": [
        "1h",
        "3h",
        "6h",
        "12h",
        "24h"
       ],
       "type": "string",
       "description": "Time between checks. Default 6h"
      },
      "price_below": {
       "type": "number",
       "description": "Optional target: an event fires when the price falls to or below this (marketplace currency)"
      },
      "min_change_pct": {
       "type": "number",
       "description": "Ignore price moves smaller than this percent. Default 1"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "key": {
       "type": "string"
      },
      "days": {
       "type": "integer"
      },
      "asins": {
       "type": "integer"
      },
      "current": {
       "type": "object",
       "properties": {
        "0735211299": {
         "type": "object",
         "properties": {
          "amazon": {
           "type": "number"
          },
          "buy_box": {
           "type": "number"
          },
          "in_stock": {
           "type": "boolean"
          },
          "new_lowest": {
           "type": "number"
          },
          "new_offers": {
           "type": "integer"
          },
          "sales_rank"
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/asin402-amazon-asin-price-stock-watcher-2940eca4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from asin402.com](https://www.zero.xyz/host/asin402.com/llms.txt)