Polymarket order book

The live order book of one market outcome: every bid and ask level (price 0-1 and size in shares), best bid and ask, spread, midpoint, last trade price, tick size, minimum order size, level counts and total size per side, and the book's timestamp. Pick the market by slug/id/url plus outcome (default the first, usually Yes), or pass the outcome's token_id. A market that has finished returns an empty book with closed true.

Every response includes credits_used: the credits this call cost.

Parameters

Every endpoint also takes fresh, raw, fields (see lean responses and caching).

Example

curl "https://api.api.sh/polymarket/v1/orderbook?slug=will-jd-vance-win-the-2028-us-presidential-election" \
  -H "x-api-key: $APISH_KEY"

import os, requests

res = requests.get(
    "https://api.api.sh/polymarket/v1/orderbook",
    params={"slug": "will-jd-vance-win-the-2028-us-presidential-election"},
    headers={"x-api-key": os.environ["APISH_KEY"]},
    timeout=120,
)
res.raise_for_status()
data = res.json()

const url = new URL("https://api.api.sh/polymarket/v1/orderbook");
url.searchParams.set("slug", "will-jd-vance-win-the-2028-us-presidential-election");

const res = await fetch(url, { headers: { "x-api-key": process.env.APISH_KEY } });
if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);
const data = await res.json();

Response

A JSON object with the fields described above, plus raw (the source's own data), cached, fetched_at and credits_used. Errors return {"success": false, "error": "…"} with the HTTP status (see errors). A lookup that ran but found nothing (404) costs the price above; refused calls and errors on our side are free (what's charged).