> ## Documentation Index > Fetch the complete documentation index at: https://docs.xo.market/llms.txt > Use this file to discover all available pages before exploring further. # Get order books > Batch order books. The response array is parallel to the request body — same length, same order. Unknown token ids return an empty book shape rather than 404 (batch endpoints don't per-element error). ## OpenAPI ````yaml /api-reference/openapi.yaml post /books openapi: 3.0.3 info: title: XO Orderbook API description: | Public REST surface of the XO CLOB API. XO mainnet chain id is `3223`. The EIP-712 order domain is `XO Market CLOB` with `verifyingContract` set to the [CTF Exchange](/) address. See [Smart accounts](../guides/smart-accounts) for the smart-account identity model and ERC-1271 order signing. Wire conventions: * Prices are trimmed decimal strings (e.g. `"0.5"`, `"0.555"`). * Sizes are decimal-string integers in human shares. * Timestamps in trade and book responses are stringified Unix seconds / milliseconds (the SDK uses `TimestampSeconds` / `TimestampMilliSeconds`). * Token IDs are decimal U256 strings; condition IDs are `0x`-prefixed 32-byte hex. version: 1.0.0 contact: name: XO Market url: https://beta.xo.market servers: - url: https://orderbooks.xo.market description: Mainnet (XO chain id 3223) security: [] tags: - name: Authentication description: >- Create and manage API keys. The L1 ClobAuth EIP-712 flow mints HMAC credentials that authenticate every other private request. - name: Market Data description: >- Public reads for books, prices, midpoints, spreads, last trades, and price history. Also includes server time and per-token configuration. - name: Markets description: >- Discovery for tradable markets, including pagination and SDK-compatible simplified shapes. - name: Trade description: Place, cancel, and inspect orders and trades for the authenticated maker. - name: Account description: Maker balance, allowance, positions, and claimable settled positions. paths: /books: post: tags: - Market Data summary: Get order books description: | Batch order books. The response array is parallel to the request body — same length, same order. Unknown token ids return an empty book shape rather than 404 (batch endpoints don't per-element error). requestBody: required: true content: application/json: schema: type: array items: type: object required: - token_id properties: token_id: type: string examples: two_sided_market: summary: both sides of a binary market value: - token_id: >- 26516164265702901957933644848127860370782874751279270726689263951695181556943 - token_id: >- 13730057904096984444199595880113152612639388204530324084054099203558669491245 responses: '200': description: OK content: application/json: schema: type: array items: $ref: '#/components/schemas/BookResponse' examples: populated: summary: both sides populated (illustrative) value: - market: >- 0x39a12d52b63969654926e095ddd96f5c459112714da03edca769aa58173c78fb asset_id: >- 26516164265702901957933644848127860370782874751279270726689263951695181556943 timestamp: '1779355812367' hash: >- 86abb2eec0fed47888ef100977aa363345a032f35a53976d88e951c28bb57ab9 bids: - price: '0.547' size: '120' asks: - price: '0.553' size: '95' min_order_size: '5' tick_size: '0.001' neg_risk: false last_trade_price: '0.550' - market: >- 0x39a12d52b63969654926e095ddd96f5c459112714da03edca769aa58173c78fb asset_id: >- 13730057904096984444199595880113152612639388204530324084054099203558669491245 timestamp: '1779355812367' hash: >- 1a2b3c4d5e6f0011223344556677889900aabbccddeeff00112233445566778899 bids: - price: '0.447' size: '95' asks: - price: '0.453' size: '120' min_order_size: '5' tick_size: '0.001' neg_risk: false last_trade_price: '0.450' x-codeSamples: - lang: Rust label: xo-orderbook-client-rs source: > use xo_orderbook_client::orderbook::{Client, Config}; use xo_orderbook_client::orderbook::types::request::OrderBookSummaryRequest; use xo_orderbook_client::types::U256; let client = Client::new("https://orderbooks.xo.market", Config::default())?; let yes = U256::from_str_radix("26516164265702901957933644848127860370782874751279270726689263951695181556943", 10)?; let no = U256::from_str_radix("13730057904096984444199595880113152612639388204530324084054099203558669491245", 10)?; let reqs = [ OrderBookSummaryRequest { token_id: yes }, OrderBookSummaryRequest { token_id: no }, ]; let books = client.order_books(&reqs).await?; // Response array is parallel to the request (same length, same order). components: schemas: BookResponse: type: object required: - market - asset_id - asks - bids - hash - timestamp - tick_size - min_order_size - neg_risk - last_trade_price properties: market: type: string description: conditionId asset_id: type: string description: Decimal U256 token id asks: type: array description: Sorted ascending by price (best ask first). items: $ref: '#/components/schemas/PriceLevel' bids: type: array description: Sorted descending by price (best bid first). items: $ref: '#/components/schemas/PriceLevel' hash: type: string description: >- keccak256 of `{bids ++ asks ++ timestamp}`; bumps on every book change. timestamp: type: string description: Unix milliseconds, stringified (TimestampMilliSeconds) tick_size: type: string example: '0.001' min_order_size: type: string description: | Minimum order size in human shares (decimal-string integer). Returns `"0"` when the gateway has no MarketInfo for the token yet (e.g. very fresh markets) — populated once engine MarketInfo arrives. neg_risk: type: boolean description: Always `false` on XO. last_trade_price: type: string description: >- Trimmed decimal; `"0.000"` if no trades have ever printed on this token. PriceLevel: type: object required: - price - size properties: price: type: string description: Trimmed decimal size: type: string description: Decimal-string integer (human shares) ````