> ## Documentation Index > Fetch the complete documentation index at: https://docs.kalshi.com/llms.txt > Use this file to discover all available pages before exploring further. # Orderbook Updates > Real-time margin orderbook price-level changes. Requirements: - authenticated connection - market specification required via `market_ticker` or `market_tickers` - sends `orderbook_snapshot` first, then incremental `orderbook_delta` updates ## AsyncAPI ````yaml perps_asyncapi.yaml orderbook_delta id: orderbook_delta title: Orderbook Updates description: | Real-time margin orderbook price-level changes. Requirements: - authenticated connection - market specification required via `market_ticker` or `market_tickers` - sends `orderbook_snapshot` first, then incremental `orderbook_delta` updates servers: - id: production protocol: wss host: external-api-margin-ws.kalshi.com bindings: [] variables: [] - id: demo protocol: wss host: external-api-margin-ws.demo.kalshi.co bindings: [] variables: [] address: orderbook_delta parameters: [] bindings: [] operations: - &ref_5 id: receiveOrderbookSnapshot title: Orderbook Snapshot type: send messages: - &ref_7 id: orderbookSnapshot contentType: application/json payload: - name: Orderbook Snapshot description: Complete view of the margin order book's aggregated price levels type: object properties: - name: type type: string description: orderbook_snapshot required: true - name: sid type: integer description: Server-generated subscription identifier required: true - name: seq type: integer description: Sequence number used for snapshot/delta consistency required: true - name: msg type: object required: true properties: - name: market_ticker type: string description: Unique market identifier required: true - name: bid type: array required: false properties: - name: item type: array description: '[price_in_dollars, contract_count_fp]' required: false properties: - name: item type: string required: false - name: ask type: array required: false properties: - name: item type: array description: '[price_in_dollars, contract_count_fp]' required: false properties: - name: item type: string required: false headers: [] jsonPayloadSchema: type: object required: - type - sid - seq - msg properties: type: type: string const: orderbook_snapshot x-parser-schema-id: sid: &ref_1 type: integer minimum: 1 description: Server-generated subscription identifier x-parser-schema-id: subscriptionId seq: &ref_2 type: integer minimum: 1 description: Sequence number used for snapshot/delta consistency x-parser-schema-id: sequenceNumber msg: type: object required: - market_ticker properties: market_ticker: &ref_3 type: string description: Unique market identifier x-parser-schema-id: marketTicker bid: type: array items: &ref_0 type: array items: type: string x-parser-schema-id: minItems: 2 maxItems: 2 description: '[price_in_dollars, contract_count_fp]' x-parser-schema-id: priceLevelDollarsCountFp x-parser-schema-id: ask: type: array items: *ref_0 x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: marginOrderbookSnapshotPayload title: Orderbook Snapshot description: Complete view of the margin order book's aggregated price levels example: No examples found bindings: [] extensions: - id: x-parser-unique-object-id value: orderbookSnapshot bindings: [] extensions: &ref_4 - id: x-parser-unique-object-id value: orderbook_delta - &ref_6 id: receiveOrderbookDelta title: Orderbook Delta type: send messages: - &ref_8 id: orderbookDelta contentType: application/json payload: - name: Orderbook Delta description: Update to be applied to the current margin order book view type: object properties: - name: type type: string description: orderbook_delta required: true - name: sid type: integer description: Server-generated subscription identifier required: true - name: seq type: integer description: Sequence number used for snapshot/delta consistency required: true - name: msg type: object required: true properties: - name: market_ticker type: string description: Unique market identifier required: true - name: price type: string required: true - name: delta type: string required: true - name: side type: string enumValues: - bid - ask required: true - name: last_update_reason type: string description: >- Margin order update reason when the delta corresponds to the authenticated user's order. enumValues: - '' - Decrease - Amend - MarginCancel - SelfTradeCancel - ExpiryCancel - Trade - PostOnlyCrossCancel required: false - name: client_order_id type: string required: false - name: subaccount type: integer required: false - name: ts_ms type: integer description: Unix timestamp in milliseconds. required: false headers: [] jsonPayloadSchema: type: object required: - type - sid - seq - msg properties: type: type: string const: orderbook_delta x-parser-schema-id: sid: *ref_1 seq: *ref_2 msg: type: object required: - market_ticker - price - delta - side properties: market_ticker: *ref_3 price: type: string x-parser-schema-id: delta: type: string x-parser-schema-id: side: type: string enum: - bid - ask x-parser-schema-id: bookSide last_update_reason: type: string enum: - '' - Decrease - Amend - MarginCancel - SelfTradeCancel - ExpiryCancel - Trade - PostOnlyCrossCancel description: >- Margin order update reason when the delta corresponds to the authenticated user's order. x-parser-schema-id: lastUpdateReason client_order_id: type: string x-parser-schema-id: subaccount: type: integer x-parser-schema-id: ts_ms: type: integer format: int64 description: Unix timestamp in milliseconds. x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: marginOrderbookDeltaPayload title: Orderbook Delta description: Update to be applied to the current margin order book view example: |- { "type": "", "sid": 123, "seq": 123, "msg": { "market_ticker": "", "price": "", "delta": "", "side": "", "last_update_reason": "", "client_order_id": "", "subaccount": 123, "ts_ms": 123 } } bindings: [] extensions: - id: x-parser-unique-object-id value: orderbookDelta bindings: [] extensions: *ref_4 sendOperations: [] receiveOperations: - *ref_5 - *ref_6 sendMessages: [] receiveMessages: - *ref_7 - *ref_8 extensions: - id: x-parser-unique-object-id value: orderbook_delta securitySchemes: - id: apiKey name: apiKey type: apiKey description: API key authentication required for margin WebSocket connections. in: user extensions: [] ````