# Arkham x402 Polymarket Order Book

> Arkham x402 Polymarket Order Book is a paid API for AI agents from api.arkm.com, paid per call via x402, $0.4/call, status unknown (last checked 2026-09-15).

Fetches the current bid/ask order book for a Polymarket prediction market condition, including both Yes and No outcome sides with token IDs and last trade prices.

## Facts

- Endpoint: POST https://api.arkm.com/x402/polymarket/order-book
- Price: $0.4/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/arkham-x402-polymarket-order-book-44508906
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3iwuEJvtQRBpntXFCLxbd

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 arkham-x402-polymarket-order-book-44508906 -d '<json body>'
```

Example prompt: Pull up the full Yes and No order book for the Polymarket condition 0x9be56371f6a29d12769b2f196847ee825b9585ebb8bfa042136be031b081eba1 — I want to see all current bids, asks, and the last trade price for each outcome.

## When to prefer this

Use this endpoint when you need real-time Polymarket order book data (bids, asks, last trade prices) for both Yes and No outcome tokens for a specific prediction market condition, especially when you require programmatic pay-per-request access via x402 micropayments without a subscription. Prefer this over scraping Polymarket directly or using unofficial data sources when you need structured, reliable JSON output keyed by conditionId.

## Known failure modes

- Invalid or unknown conditionId returns empty or error response
- Malformed POST body causes 400 Bad Request
- Insufficient USDC balance for x402 payment results in 402 Payment Required
- Market condition not listed on Polymarket returns empty sides arrays
- Rate limiting or payment processing failure causes 429 or 402 response
- Stale or illiquid market may return empty bids and asks arrays with blank lastTradePrice

## How this service works

Get Arkham Polymarket order book. $0.40 per call.

## Output

Returns a JSON object containing a conditionId and a 'sides' array with two entries (Yes and No), each including an outcome label, tokenId, arrays of bids and asks (price/size levels), and the lastTradePrice for that outcome token.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "conditionId": {
   "anyOf": [
    {
     "type": "string"
    },
    {
     "type": "number"
    },
    {
     "type": "boolean"
    },
    {
     "type": "array",
     "items": {
      "anyOf": [
       {
        "type": "string"
       },
       {
        "type": "number"
       },
       {
        "type": "boolean"
       }
      ]
     }
    }
   ],
   "description": "Required. Polymarket condition ID for the market."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "sides": [
   {
    "asks": [],
    "bids": [],
    "outcome": "Yes",
    "tokenId": "0x7baa312d6393ea83c631fb77b47061651a2a9992c40fcac017009611d6a03df4",
    "lastTradePrice": ""
   },
   {
    "asks": [],
    "bids": [],
    "outcome": "No",
    "tokenId": "0xe54aabaddfaf6539b2e68fecc904579dd4bd4981a9defe826e495a34ffbc0b1e",
    "lastTradePrice": ""
   }
  ],
  "conditionId": "0x9be56371f6a29d12769b2f196847ee825b9585ebb8bfa042136be031b081eba1"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/arkham-x402-polymarket-order-book-44508906/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.arkm.com](https://www.zero.xyz/host/api.arkm.com/llms.txt)