> ## 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 - supports `get_snapshot` on `update_subscription` to request a fresh snapshot without changing the subscription ## 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 - supports `get_snapshot` on `update_subscription` to request a fresh snapshot without changing the subscription 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_6 id: receiveOrderbookSnapshot title: Orderbook Snapshot type: send messages: - &ref_8 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: id type: integer description: > Unique ID of the command request. Generated by the client and should be unique within a WS session. The simplest way to use it would be to start from 1 and then increment the value for every new command sent to the server. If the id is set to 0, the server treats it the same way as if there was no id. required: false - name: sid type: integer description: >- Server-generated subscription identifier (sid) used to identify the channel required: true - name: seq type: integer description: >- Sequential number that should be checked if you want to guarantee you received all the messages. 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 - name: sending_ts_ms type: integer description: >- Unix timestamp in milliseconds when Kalshi queued this message at the network layer. required: false headers: [] jsonPayloadSchema: type: object required: - type - sid - seq - msg properties: type: type: string const: orderbook_snapshot x-parser-schema-id: id: type: integer description: > Unique ID of the command request. Generated by the client and should be unique within a WS session. The simplest way to use it would be to start from 1 and then increment the value for every new command sent to the server. If the id is set to 0, the server treats it the same way as if there was no id. minimum: 0 x-parser-schema-id: commandId sid: &ref_1 type: integer description: >- Server-generated subscription identifier (sid) used to identify the channel minimum: 1 x-parser-schema-id: subscriptionId seq: &ref_2 type: integer description: >- Sequential number that should be checked if you want to guarantee you received all the messages. Used for snapshot/delta consistency minimum: 1 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: sending_ts_ms: &ref_4 type: integer format: int64 description: >- Unix timestamp in milliseconds when Kalshi queued this message at the network layer. x-parser-schema-id: sendingTimestampMs 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_5 - id: x-parser-unique-object-id value: orderbook_delta - &ref_7 id: receiveOrderbookDelta title: Orderbook Delta type: send messages: - &ref_9 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 (sid) used to identify the channel required: true - name: seq type: integer description: >- Sequential number that should be checked if you want to guarantee you received all the messages. 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. The value ReduceOnlyCancel means reduce_only capped the order at placement. The field is omitted when no reason applies. enumValues: - Decrease - Amend - MarginCancel - SelfTradeCancel - ExpiryCancel - CloseCancel - HaltCancel - Trade - PostOnlyCrossCancel - ReduceOnlyCancel required: false - name: client_order_id type: string required: false - name: ts_ms type: integer description: Unix timestamp in milliseconds. required: false - name: subaccount type: integer required: false - name: sending_ts_ms type: integer description: >- Unix timestamp in milliseconds when Kalshi queued this message at the network layer. 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-rust-type: common::types::Price x-rust-serialize-with: ws::dto::serde_money::serialize_price_dollars x-parser-schema-id: delta: type: string x-rust-type: i64 x-rust-serialize-with: ws::dto::serde_money::serialize_centicount_fixed_point_count 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 - CloseCancel - HaltCancel - Trade - PostOnlyCrossCancel - ReduceOnlyCancel description: >- Margin order update reason. The value ReduceOnlyCancel means reduce_only capped the order at placement. The field is omitted when no reason applies. x-parser-schema-id: lastUpdateReason client_order_id: type: string x-parser-schema-id: ts_ms: type: integer format: int64 description: Unix timestamp in milliseconds. x-parser-schema-id: subaccount: type: integer x-parser-schema-id: x-parser-schema-id: sending_ts_ms: *ref_4 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": "", "ts_ms": 123, "subaccount": 123 }, "sending_ts_ms": 123 } bindings: [] extensions: - id: x-parser-unique-object-id value: orderbookDelta bindings: [] extensions: *ref_5 sendOperations: [] receiveOperations: - *ref_6 - *ref_7 sendMessages: [] receiveMessages: - *ref_8 - *ref_9 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: [] ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.