> ## Documentation Index > Fetch the complete documentation index at: https://docs.polymarket.com/llms.txt > Use this file to discover all available pages before exploring further. # Book > Perps WebSocket order book updates. ## AsyncAPI ````yaml asyncapi-perps.json book id: book title: Book description: Order book snapshot updates. Pushed every 100ms. servers: - id: production protocol: wss host: ws.perpetuals.polymarket.com bindings: [] variables: [] address: /v1/ws parameters: [] bindings: [] operations: - &ref_1 id: BookSubscribe title: Book subscribe description: Subscribe to book type: receive messages: - &ref_6 id: SubscribeRequest contentType: application/json payload: - name: Subscribe description: Subscribe to order book updates for an instrument type: object properties: - name: id type: integer description: Correlation ID for request-response matching required: false - name: req type: string description: Request type enumValues: - post - sub - unsub required: true - name: chs type: array description: Book subscription in format "book::{iid}" (e.g., "book::1") required: true properties: - name: item type: string required: false headers: [] jsonPayloadSchema: type: object title: Base Request properties: id: type: integer description: Correlation ID for request-response matching x-parser-schema-id: req: type: string description: Request type enum: - post - sub - unsub x-parser-schema-id: chs: type: array description: Book subscription in format "book::{iid}" (e.g., "book::1") items: type: string pattern: ^book::\d+$ x-parser-schema-id: example: - book::1 x-parser-schema-id: required: - req - chs x-parser-schema-id: title: Subscribe description: Subscribe to order book updates for an instrument example: |- { "req": "sub", "chs": [ "book::1" ] } bindings: [] extensions: - id: x-parser-unique-object-id value: SubscribeRequest bindings: [] extensions: &ref_0 - id: x-parser-unique-object-id value: book - &ref_3 id: BookSubscribeResponse title: Book subscribe response description: Book subscribe response type: send messages: - &ref_8 id: SubscribeResponse contentType: application/json payload: - name: Subscribe Response description: Response to book subscribe request type: object properties: - name: id type: integer description: Correlation ID for request-response matching required: false - name: data type: array title: Subscribe Response required: true properties: - name: item type: object required: false properties: - name: status type: string enumValues: - ok required: true - name: status type: string enumValues: - err required: true - name: error type: string description: >- Error identifier. For domain rejections and transport errors (`401`/`404`/`429`/`500`) this is a stable, machine-readable snake_case identifier that is part of the API contract and safe to branch on, e.g. `insufficient_margin`, `insufficient_balance`, `order_not_found`, `reduce_only_invalid`, `unauthorized`, `not_found`. For `400` it is a human-readable validation detail whose wording may change. See the Error handling guide for the domain identifiers. (Post-only / Fill-or-Kill outcomes are order statuses such as `post_only_rejected`, not rejections.) required: true headers: [] jsonPayloadSchema: type: object title: Base Response properties: id: type: integer description: Correlation ID for request-response matching x-parser-schema-id: data: title: Subscribe Response type: array items: oneOf: - type: object required: - status properties: status: type: string enum: - ok x-parser-schema-id: x-parser-schema-id: - type: object required: - status - error properties: status: type: string enum: - err x-parser-schema-id: error: type: string description: >- Error identifier. For domain rejections and transport errors (`401`/`404`/`429`/`500`) this is a stable, machine-readable snake_case identifier that is part of the API contract and safe to branch on, e.g. `insufficient_margin`, `insufficient_balance`, `order_not_found`, `reduce_only_invalid`, `unauthorized`, `not_found`. For `400` it is a human-readable validation detail whose wording may change. See the Error handling guide for the domain identifiers. (Post-only / Fill-or-Kill outcomes are order statuses such as `post_only_rejected`, not rejections.) example: insufficient_margin x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: required: - data x-parser-schema-id: title: Subscribe Response description: Response to book subscribe request example: |- { "data": [] } bindings: [] extensions: - id: x-parser-unique-object-id value: SubscribeResponse bindings: [] extensions: *ref_0 - &ref_2 id: BookUnsubscribe title: Book unsubscribe description: Unsubscribe from book type: receive messages: - &ref_7 id: UnsubscribeRequest contentType: application/json payload: - name: Unsubscribe description: Unsubscribe from order book updates type: object properties: - name: id type: integer description: Correlation ID for request-response matching required: false - name: req type: string description: Request type enumValues: - post - sub - unsub required: true - name: chs type: array description: Book subscription in format "book::{iid}" (e.g., "book::1") required: true properties: - name: item type: string required: false headers: [] jsonPayloadSchema: type: object title: Base Request properties: id: type: integer description: Correlation ID for request-response matching x-parser-schema-id: req: type: string description: Request type enum: - post - sub - unsub x-parser-schema-id: chs: type: array description: Book subscription in format "book::{iid}" (e.g., "book::1") items: type: string pattern: ^book::\d+$ x-parser-schema-id: example: - book::1 x-parser-schema-id: required: - req - chs x-parser-schema-id: title: Unsubscribe description: Unsubscribe from order book updates example: |- { "req": "unsub", "chs": [ "book::1" ] } bindings: [] extensions: - id: x-parser-unique-object-id value: UnsubscribeRequest bindings: [] extensions: *ref_0 - &ref_4 id: BookUnsubscribeResponse title: Book unsubscribe response description: Book unsubscribe response type: send messages: - &ref_9 id: UnsubscribeResponse contentType: application/json payload: - name: Unsubscribe Response description: Response to book unsubscribe request type: object properties: - name: id type: integer description: Correlation ID for request-response matching required: false - name: data type: array title: Subscribe Response required: true properties: - name: item type: object required: false properties: - name: status type: string enumValues: - ok required: true - name: status type: string enumValues: - err required: true - name: error type: string description: >- Error identifier. For domain rejections and transport errors (`401`/`404`/`429`/`500`) this is a stable, machine-readable snake_case identifier that is part of the API contract and safe to branch on, e.g. `insufficient_margin`, `insufficient_balance`, `order_not_found`, `reduce_only_invalid`, `unauthorized`, `not_found`. For `400` it is a human-readable validation detail whose wording may change. See the Error handling guide for the domain identifiers. (Post-only / Fill-or-Kill outcomes are order statuses such as `post_only_rejected`, not rejections.) required: true headers: [] jsonPayloadSchema: type: object title: Base Response properties: id: type: integer description: Correlation ID for request-response matching x-parser-schema-id: data: title: Subscribe Response type: array items: oneOf: - type: object required: - status properties: status: type: string enum: - ok x-parser-schema-id: x-parser-schema-id: - type: object required: - status - error properties: status: type: string enum: - err x-parser-schema-id: error: type: string description: >- Error identifier. For domain rejections and transport errors (`401`/`404`/`429`/`500`) this is a stable, machine-readable snake_case identifier that is part of the API contract and safe to branch on, e.g. `insufficient_margin`, `insufficient_balance`, `order_not_found`, `reduce_only_invalid`, `unauthorized`, `not_found`. For `400` it is a human-readable validation detail whose wording may change. See the Error handling guide for the domain identifiers. (Post-only / Fill-or-Kill outcomes are order statuses such as `post_only_rejected`, not rejections.) example: insufficient_margin x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: required: - data x-parser-schema-id: title: Unsubscribe Response description: Response to book unsubscribe request example: |- { "data": [] } bindings: [] extensions: - id: x-parser-unique-object-id value: UnsubscribeResponse bindings: [] extensions: *ref_0 - &ref_5 id: BookUpdate title: Book update description: Receive book updates type: send messages: - &ref_10 id: Update contentType: application/json payload: - name: Update description: Real-time order book updates for subscribed instruments type: object properties: - name: ch type: string description: >- Channel name for push data. Parameterized channels include the instrument ID (e.g. "trades::1", "book::1", "klines::1::1m", "tickers::all"). Private channels use plain names (e.g. "fills", "orders"). required: true - name: ts type: integer description: >- Request timestamp. Unix milliseconds for most operations; Unix seconds for withdrawals (must match the on-chain EIP-712 struct verified against block.timestamp). required: true - name: sq type: integer description: Sequence number required: true - name: data type: object required: true properties: - name: b type: array description: Bid levels required: true properties: - name: item type: array description: | - `"100.00"` - Price - `"10.00"` - Quantity required: false properties: - name: item type: string required: false - name: a type: array description: Ask levels required: true properties: - name: item type: array description: | - `"100.00"` - Price - `"10.00"` - Quantity required: false properties: - name: item type: string required: false headers: [] jsonPayloadSchema: title: Book Update type: object properties: ch: type: string description: >- Channel name for push data. Parameterized channels include the instrument ID (e.g. "trades::1", "book::1", "klines::1::1m", "tickers::all"). Private channels use plain names (e.g. "fills", "orders"). example: trades::1 x-parser-schema-id: ts: type: integer description: >- Request timestamp. Unix milliseconds for most operations; Unix seconds for withdrawals (must match the on-chain EIP-712 struct verified against block.timestamp). example: 1767225600000 x-parser-schema-id: sq: type: integer description: Sequence number example: 1234567890 x-parser-schema-id: data: type: object required: - b - a properties: b: type: array items: type: array items: type: string x-parser-schema-id: maxItems: 2 description: | - `"100.00"` - Price - `"10.00"` - Quantity example: - '100.00' - '10.00' x-parser-schema-id: description: Bid levels x-parser-schema-id: a: type: array items: type: array items: type: string x-parser-schema-id: maxItems: 2 description: | - `"100.00"` - Price - `"10.00"` - Quantity example: - '100.00' - '10.00' x-parser-schema-id: description: Ask levels x-parser-schema-id: x-parser-schema-id: required: - ch - ts - sq - data x-parser-schema-id: title: Update description: Real-time order book updates for subscribed instruments example: |- { "ch": "book::1", "ts": 1767225600000, "sq": 1234567890, "data": { "b": [ [ "100.00", "10.00" ] ], "a": [ [ "100.00", "10.00" ] ] } } bindings: [] extensions: - id: x-parser-unique-object-id value: Update bindings: [] extensions: *ref_0 sendOperations: - *ref_1 - *ref_2 receiveOperations: - *ref_3 - *ref_4 - *ref_5 sendMessages: - *ref_6 - *ref_7 receiveMessages: - *ref_8 - *ref_9 - *ref_10 extensions: - id: x-parser-unique-object-id value: book securitySchemes: [] ````