# SiteCheck Polymarket Order Book

> SiteCheck Polymarket Order Book is a paid API for AI agents from api.sitecheck-api.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-16).

Fetches the current order book (bids, asks, spread, depth) for a Polymarket prediction market outcome token

## Facts

- Endpoint: GET https://api.sitecheck-api.workers.dev/api/pm/orderbook?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-polymarket-order-book-a857a039
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IcKzUj0ytd2NbO49zxzLb

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 sitecheck-polymarket-order-book-a857a039
```

Example prompt: Pull the current order book for the Polymarket outcome token ID 98961942092312242488092499568359433586418736677157512843097593070222397872380 — I want to see the best bid, best ask, spread, and how much liquidity is within 5 cents of the mid price.

## When to prefer this

Choose this endpoint when you need real-time Polymarket prediction market order book data including bids, asks, spread, and depth. It directly proxies the Polymarket CLOB API and supports lookup by numeric token ID or by market slug and outcome name. Prefer this over generic crypto exchange order book endpoints when the target is a Polymarket prediction market rather than a spot or futures asset.

## Known failure modes

- Missing or invalid tokenId returns an error — tokenId is required unless slug+outcome are provided
- Unknown slug or outcome name returns no data
- Polymarket CLOB API unavailability causes upstream failure
- Token ID for a resolved/delisted market may return empty or stale order book
- Network timeout on the Polymarket CLOB API results in a gateway error

## How this service works

Fetches resting order book depth for a Polymarket outcome token (or market slug and outcome name). Returns top 20 bids and asks, midpoint price, spread, depth within 1/2/5 cents, and last trade price. Information only, not financial advice.

## Output

Returns a structured JSON object containing the full order book: arrays of bid and ask orders (each with price and size), best bid, best ask, mid price, spread, number of bids and asks, market address, source (Polymarket CLOB API), and order book depth metrics showing liquidity within 1, 2, and 5 cents of the mid price on both sides. Also includes the last trade price and a timestamp of when the data was fetched.

## 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": [
      "tokenId"
     ],
     "properties": {
      "slug": {
       "type": "string",
       "description": "Market slug if tokenId is unknown"
      },
      "outcome": {
       "type": "string",
       "description": "Outcome name (e.g. Yes or No) when slug is provided"
      },
      "tokenId": {
       "type": "string",
       "description": "Outcome CLOB token ID (numeric string)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "mid": 0.635,
  "asks": [
   {
    "size": 577,
    "price": 0.64
   },
   {
    "size": 2691.99,
    "price": 0.65
   },
   {
    "size": 1261.03,
    "price": 0.66
   }
  ],
  "bids": [
   {
    "size": 362.87,
    "price": 0.63
   },
   {
    "size": 812.33,
    "price": 0.62
   },
   {
    "size": 100,
    "price": 0.61
   }
  ],
  "depth": {
   "asksWithin1Cent": 3268.99,
   "bidsWithin1Cent": 1175.2,
   "asksWithin2Cents": 4530.02,
   "asksWithin5Cents": 4810.02,
   "bidsWithin2Cents": 1275.2,
   "bidsWithin5Cents": 1747.07
  },
  "market": "0xadebf2aec917971a733f74c66387529b3347ebf0f3019410427921d28e921beb",
  "source": "Polymarket CLOB API (clob.polymarket.com/book)",
  "spread": 0.01,
  "bestAsk": 0.64,
  "bestBid": 0.63,
  "tokenId": "98961942092312242488092499568359433586418736677157512843097593070222397872380",
  "asksCount": 16,
  "bidsCount": 24,
  "checkedAt": "2026-10-15T18:21:04.652Z",
  "disclaimer": "Information only, not financial advice.",
  "lastTradePrice": 0.39
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-polymarket-order-book-a857a039/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.sitecheck-api.workers.dev](https://www.zero.xyz/host/api.sitecheck-api.workers.dev/llms.txt)