polymarket.book

stable Standard

CLOB order book for an outcome token.

GET /v1/polymarket/book

What you get#

One Polymarket record in Onekey's unified shape, in data. If the record does not exist you get a 404 not_found and are not charged.

What it costs#

Standard · 1 credit for a fresh fetch, charged only when it succeeds.
Free when served from cache (0.2 credit for a cached response over 100 KB).
Free if the request is invalid (never charged) or the source fails or reports not found (refunded).

Parameters#

Name	Type	Required	Default	What it is	Constraints
`token_id`	string	yes	(required)	CLOB outcome token id (from a market's clobTokenIds)	max 90 chars; must match `\d{10,90}`; trimmed

Request#

curl "https://api.onekey.dev/v1/polymarket/book?token_id=39223330966352513418907732239455948906399882924787587183466504819170775983376" \
  -H "x-api-key: YOUR_API_KEY"

Try it

Add your key to run this call right here. No key? Get one free. The key stays in this tab.

Recorded response#

A real Polymarket response, recorded and returned in Onekey's shape. Fields the platform does not provide are null.

json

{
  "success": true,
  "data": {
    "entity": {
      "id": "39223330966352513418907732239455948906399882924787587183466504819170775983376",
      "date": "2026-09-28T20:08:17Z"
    },
    "ext": {
      "conditionId": "0x836b850fc838195374862551a36f1c8691d96ff01e58b0a071f0fc1a0e357fb1",
      "tickSize": 0.001,
      "minOrderSize": 5,
      "bestBidSize": null,
      "bestAskSize": 1530988.79,
      "bids": [],
      "asks": [
        {
          "price": "0.999",
          "size": "6066355.72"
        },
        {
          "price": "0.998",
          "size": "271864.64"
        },
        {
          "price": "0.001",
          "size": "1530988.79"
        }
      ]
    },
    "market": {
      "price": 0.001,
      "bid": null,
      "ask": 0.001
    }
  },
  "metadata": {
    "platform": "polymarket",
    "endpoint": "book",
    "cached": false,
    "stale": false,
    "age_s": 0,
    "fetched_at": "2026-01-01T12:00:00+00:00",
    "credits_charged": 1,
    "request_id": "7f3a9c2e5b1d4c8fa2e6d0b9c4f18e37"
  },
  "error": null
}

Field mapping#

How this endpoint's source fields become Onekey's unified schema. Fields the source lacks come back as null.

Source path	Onekey field	Transform
`asset_id`	`entity.id`	-
`market`	`ext.conditionId`	-
`timestamp`	`entity.date`	`toIsoDate`
`last_trade_price`	`market.price`	`toNumber`
`tick_size`	`ext.tickSize`	`toNumber`
`min_order_size`	`ext.minOrderSize`	`toNumber`
`bids.-1.price`	`market.bid`	`toNumber`
`bids.-1.size`	`ext.bestBidSize`	`toNumber`
`asks.-1.price`	`market.ask`	`toNumber`
`asks.-1.size`	`ext.bestAskSize`	`toNumber`
`bids`	`ext.bids`	-
`asks`	`ext.asks`	-

Caching and freshness#

Fresh for about 30 seconds. Repeat calls in that window are served from cache and are free.
Between 30 seconds and 5 minutes the cached copy is still served instantly and marked stale: true while Onekey refreshes it in the background.
If the source is down when a refresh is needed, the last copy can be served for up to 1 hour more (marked stale).
A "not found" is remembered for 1 minute and is free.
The cache is shared across all customers, which is what keeps repeat calls cheap.

What can go wrong#

Status	Code	What to do
401	`unauthorized`	Check the `x-api-key` header.
402	`insufficient_credits`	Add credits; your balance must cover the price.
404	`not_found`	That record does not exist. Free; do not retry.
422	`invalid_params`	Fix the parameters using the table above. Free.
429	`rate_limited`	Wait `Retry-After` seconds, then retry.
502	`upstream_error`	The source failed. Refunded; retry with backoff.

See Errors for the full list and retry guidance.

Status: stable (verified against the live source).