Kalshi WebSocket Streaming API

asyncapi: '2.6.0'
info:
  title: Kalshi WebSocket Streaming API
  version: '2.0.0'
  description: >-
    Real-time WebSocket streaming feed for the Kalshi CFTC-regulated event
    contracts exchange. Publishes orderbook updates, public trades, market
    tickers, user orders, user fills, market positions, market and event
    lifecycle notifications, RFQ communications, and order group updates. All
    subscriptions are multiplexed over a single authenticated WebSocket
    connection using JSON command frames (cmd: subscribe / unsubscribe /
    update_subscription). Authenticated channels (fill, user_orders,
    market_positions, communications, order_group_updates) require API key
    authentication during the WebSocket handshake.
  contact:
    name: Kalshi
    url: https://docs.kalshi.com/api-reference
  license:
    name: Kalshi Developer Agreement
    url: https://kalshi.com/developer-agreement
servers:
  production:
    url: external-api-ws.kalshi.com
    protocol: wss
    description: Production Kalshi WebSocket endpoint.
    security:
      - apiKey: []
defaultContentType: application/json
channels:
  /:
    description: >-
      Single multiplexed WebSocket endpoint. Clients send subscribe /
      unsubscribe / update_subscription commands and receive channel messages
      and acknowledgements over the same connection.
    publish:
      operationId: sendClientCommand
      summary: Send a command frame (subscribe, unsubscribe, update_subscription).
      message:
        oneOf:
          - $ref: '#/components/messages/SubscribeCommand'
          - $ref: '#/components/messages/UnsubscribeCommand'
          - $ref: '#/components/messages/UpdateSubscriptionCommand'
    subscribe:
      operationId: receiveServerMessage
      summary: Receive channel messages and control replies from Kalshi.
      message:
        oneOf:
          - $ref: '#/components/messages/SubscribedAck'
          - $ref: '#/components/messages/ErrorMessage'
          - $ref: '#/components/messages/OrderbookSnapshot'
          - $ref: '#/components/messages/OrderbookDelta'
          - $ref: '#/components/messages/Ticker'
          - $ref: '#/components/messages/Trade'
          - $ref: '#/components/messages/Fill'
          - $ref: '#/components/messages/UserOrder'
          - $ref: '#/components/messages/MarketPosition'
          - $ref: '#/components/messages/MarketLifecycleV2'
          - $ref: '#/components/messages/EventLifecycle'
          - $ref: '#/components/messages/EventFeeUpdate'
          - $ref: '#/components/messages/MultivariateMarketLifecycle'
          - $ref: '#/components/messages/MultivariateLookup'
          - $ref: '#/components/messages/Communications'
          - $ref: '#/components/messages/OrderGroupUpdates'
components:
  securitySchemes:
    apiKey:
      type: httpApiKey
      name: KALSHI-ACCESS-KEY
      in: header
      description: >-
        API key authentication is performed during the WebSocket handshake.
        Authenticated channels (fill, user_orders, market_positions,
        communications, order_group_updates) require a valid Kalshi API key
        with Ed25519 request signatures as described in the REST API reference.
  messages:
    SubscribeCommand:
      name: SubscribeCommand
      title: Subscribe Command
      summary: Subscribe to one or more channels.
      payload:
        type: object
        required: [id, cmd, params]
        properties:
          id:
            type: integer
            description: Client-assigned command id, starting at 1.
          cmd:
            type: string
            enum: [subscribe]
          params:
            type: object
            required: [channels]
            properties:
              channels:
                type: array
                description: >-
                  Channels to subscribe to. Supported channels:
                  orderbook_delta, ticker, trade, fill, user_orders,
                  market_positions, market_lifecycle_v2, event_lifecycle,
                  multivariate_market_lifecycle, multivariate, communications,
                  order_group_updates.
                items:
                  type: string
                  enum:
                    - orderbook_delta
                    - ticker
                    - trade
                    - fill
                    - user_orders
                    - market_positions
                    - market_lifecycle_v2
                    - event_lifecycle
                    - multivariate_market_lifecycle
                    - multivariate
                    - communications
                    - order_group_updates
              market_ticker:
                type: string
              market_tickers:
                type: array
                items:
                  type: string
              send_initial_snapshot:
                type: boolean
                description: Request initial snapshot on the ticker channel.
              use_yes_price:
                type: boolean
                description: Use yes-side pricing format for orderbook_delta.
              shard_factor:
                type: integer
                minimum: 1
                maximum: 100
                description: Shard fanout factor for communications channel.
              shard_key:
                type: integer
                description: Shard key (0 <= shard_key < shard_factor).
    UnsubscribeCommand:
      name: UnsubscribeCommand
      title: Unsubscribe Command
      payload:
        type: object
        required: [id, cmd, params]
        properties:
          id:
            type: integer
          cmd:
            type: string
            enum: [unsubscribe]
          params:
            type: object
            required: [sids]
            properties:
              sids:
                type: array
                items:
                  type: integer
                description: Server-assigned subscription ids to unsubscribe.
    UpdateSubscriptionCommand:
      name: UpdateSubscriptionCommand
      title: Update Subscription Command
      summary: Add or remove markets from an existing subscription, or fetch a snapshot.
      payload:
        type: object
        required: [id, cmd, params]
        properties:
          id:
            type: integer
          cmd:
            type: string
            enum: [update_subscription]
          params:
            type: object
            required: [sid, action]
            properties:
              sid:
                type: integer
              action:
                type: string
                enum: [add_markets, delete_markets, get_snapshot]
              market_tickers:
                type: array
                items:
                  type: string
    SubscribedAck:
      name: SubscribedAck
      title: Subscribed Acknowledgement
      payload:
        type: object
        properties:
          id:
            type: integer
          type:
            type: string
            enum: [subscribed]
          msg:
            type: object
            properties:
              channel:
                type: string
              sid:
                type: integer
    ErrorMessage:
      name: ErrorMessage
      title: Error
      payload:
        type: object
        properties:
          id:
            type: integer
          type:
            type: string
            enum: [error]
          msg:
            type: object
            properties:
              code:
                type: integer
              msg:
                type: string
    OrderbookSnapshot:
      name: OrderbookSnapshot
      title: Orderbook Snapshot
      summary: Full orderbook snapshot for a market (orderbook_delta channel).
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [orderbook_snapshot]
          sid:
            type: integer
          seq:
            type: integer
          msg:
            type: object
            properties:
              market_ticker:
                type: string
              market_id:
                type: string
                format: uuid
              yes_dollars_fp:
                type: array
                description: YES side price levels [price_in_dollars, contract_count_fp].
                items:
                  type: array
              no_dollars_fp:
                type: array
                description: NO side price levels [price_in_dollars, contract_count_fp].
                items:
                  type: array
    OrderbookDelta:
      name: OrderbookDelta
      title: Orderbook Delta
      summary: Incremental orderbook update.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [orderbook_delta]
          sid:
            type: integer
          seq:
            type: integer
          msg:
            type: object
            properties:
              market_ticker:
                type: string
              market_id:
                type: string
                format: uuid
              price_dollars:
                type: string
              delta_fp:
                type: string
                description: Fixed-point contract delta (2 decimals).
              side:
                type: string
                enum: [yes, no]
              client_order_id:
                type: string
              subaccount:
                type: integer
              ts_ms:
                type: integer
    Ticker:
      name: Ticker
      title: Market Ticker
      summary: Market price, volume, and open interest update.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [ticker]
          sid:
            type: integer
          msg:
            type: object
            properties:
              market_ticker:
                type: string
              market_id:
                type: string
                format: uuid
              price_dollars:
                type: string
              yes_bid_dollars:
                type: string
              yes_ask_dollars:
                type: string
              volume_fp:
                type: string
              open_interest_fp:
                type: string
              dollar_volume:
                type: integer
              dollar_open_interest:
                type: integer
              yes_bid_size_fp:
                type: string
              yes_ask_size_fp:
                type: string
              last_trade_size_fp:
                type: string
              ts_ms:
                type: integer
    Trade:
      name: Trade
      title: Public Trade
      summary: Public trade execution notification.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [trade]
          sid:
            type: integer
          msg:
            type: object
            properties:
              trade_id:
                type: string
                format: uuid
              market_ticker:
                type: string
              yes_price_dollars:
                type: string
              no_price_dollars:
                type: string
              count_fp:
                type: string
              taker_side:
                type: string
                enum: [yes, no]
              taker_outcome_side:
                type: string
                enum: [yes, no]
              taker_book_side:
                type: string
                enum: [bid, ask]
              ts_ms:
                type: integer
              ts:
                type: integer
                description: Deprecated, seconds.
    Fill:
      name: Fill
      title: User Fill
      summary: Notification of a fill on one of your orders (authenticated).
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [fill]
          sid:
            type: integer
          msg:
            type: object
            properties:
              trade_id:
                type: string
                format: uuid
              order_id:
                type: string
                format: uuid
              market_ticker:
                type: string
              is_taker:
                type: boolean
              side:
                type: string
                enum: [yes, no]
              yes_price_dollars:
                type: string
              count_fp:
                type: string
              fee_cost:
                type: string
              action:
                type: string
                enum: [buy, sell]
              ts_ms:
                type: integer
              post_position_fp:
                type: string
              purchased_side:
                type: string
                enum: [yes, no]
              outcome_side:
                type: string
                enum: [yes, no]
              book_side:
                type: string
                enum: [bid, ask]
              client_order_id:
                type: string
              subaccount:
                type: integer
    UserOrder:
      name: UserOrder
      title: User Order
      summary: Real-time order created/updated notification (authenticated).
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [user_order]
          sid:
            type: integer
          msg:
            type: object
            properties:
              order_id:
                type: string
                format: uuid
              ticker:
                type: string
              status:
                type: string
                enum: [resting, canceled, executed]
              side:
                type: string
                enum: [yes, no]
              outcome_side:
                type: string
                enum: [yes, no]
              yes_price_dollars:
                type: string
              fill_count_fp:
                type: string
              remaining_count_fp:
                type: string
              created_ts_ms:
                type: integer
    MarketPosition:
      name: MarketPosition
      title: Market Position
      summary: Real-time per-market position update (authenticated).
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [market_position]
          sid:
            type: integer
          msg:
            type: object
            properties:
              user_id:
                type: string
              market_ticker:
                type: string
              position_fp:
                type: string
              position_cost_dollars:
                type: string
              realized_pnl_dollars:
                type: string
              fees_paid_dollars:
                type: string
              position_fee_cost_dollars:
                type: string
              volume_fp:
                type: string
              subaccount:
                type: integer
    MarketLifecycleV2:
      name: MarketLifecycleV2
      title: Market Lifecycle v2
      summary: Market state transitions and lifecycle events.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [market_lifecycle_v2]
          sid:
            type: integer
          msg:
            type: object
            required: [event_type, market_ticker]
            properties:
              event_type:
                type: string
                enum:
                  - created
                  - activated
                  - deactivated
                  - close_date_updated
                  - determined
                  - settled
                  - price_level_structure_updated
                  - metadata_updated
              market_ticker:
                type: string
              open_ts:
                type: integer
              close_ts:
                type: integer
              determination_ts:
                type: integer
              settled_ts:
                type: integer
              result:
                type: string
              settlement_value:
                type: string
              is_deactivated:
                type: boolean
              price_level_structure:
                type: string
                enum: [linear_cent, deci_cent, tapered_deci_cent]
              floor_strike:
                type: string
              yes_sub_title:
                type: string
              additional_metadata:
                type: object
    EventLifecycle:
      name: EventLifecycle
      title: Event Lifecycle
      summary: Event creation notification.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [event_lifecycle]
          sid:
            type: integer
          msg:
            type: object
            required: [event_ticker, title, subtitle, collateral_return_type, series_ticker]
            properties:
              event_ticker:
                type: string
              title:
                type: string
              subtitle:
                type: string
              collateral_return_type:
                type: string
                enum: [MECNET, DIRECNET, '']
              series_ticker:
                type: string
              strike_date:
                type: string
              strike_period:
                type: string
    EventFeeUpdate:
      name: EventFeeUpdate
      title: Event Fee Update
      summary: Event-level fee override updates.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [event_fee_update]
          sid:
            type: integer
          msg:
            type: object
            properties:
              event_ticker:
                type: string
              fee_type_override:
                type: string
                enum: [quadratic, quadratic_with_maker_fees, flat]
                nullable: true
              fee_multiplier_override:
                type: string
                nullable: true
    MultivariateMarketLifecycle:
      name: MultivariateMarketLifecycle
      title: Multivariate Market Lifecycle
      summary: Lifecycle notifications for multivariate markets.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [multivariate_market_lifecycle]
          sid:
            type: integer
          msg:
            type: object
            required: [event_type, market_ticker]
            properties:
              event_type:
                type: string
                enum:
                  - created
                  - activated
                  - deactivated
                  - close_date_updated
                  - determined
                  - settled
                  - price_level_structure_updated
                  - metadata_updated
              market_ticker:
                type: string
              open_ts:
                type: integer
              close_ts:
                type: integer
              result:
                type: string
              determination_ts:
                type: integer
              settlement_value:
                type: string
              settled_ts:
                type: integer
              is_deactivated:
                type: boolean
              price_level_structure:
                type: string
                enum: [linear_cent, deci_cent, tapered_deci_cent]
              floor_strike:
                type: string
              yes_sub_title:
                type: string
    MultivariateLookup:
      name: MultivariateLookup
      title: Multivariate Lookup (Deprecated)
      summary: >-
        Legacy multivariate lookup notification. Deprecated - predates RFQs and
        should not be used for new integrations.
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [multivariate_lookup]
          sid:
            type: integer
          msg:
            type: object
            properties:
              collection_ticker:
                type: string
              event_ticker:
                type: string
              market_ticker:
                type: string
              selected_markets:
                type: array
                items:
                  type: object
                  properties:
                    event_ticker:
                      type: string
                    market_ticker:
                      type: string
                    side:
                      type: string
                      enum: [yes, no]
    Communications:
      name: Communications
      title: Communications (RFQ / Quotes)
      summary: >-
        Real-time RFQ (Request for Quote) and quote lifecycle events
        (authenticated). Message types: RFQCreated, RFQDeleted, QuoteCreated,
        QuoteAccepted, QuoteExecuted.
      payload:
        type: object
        properties:
          type:
            type: string
            enum:
              - rfq_created
              - rfq_deleted
              - quote_created
              - quote_accepted
              - quote_executed
          sid:
            type: integer
          msg:
            type: object
            properties:
              id:
                type: string
              quote_id:
                type: string
              rfq_id:
                type: string
              order_id:
                type: string
              client_order_id:
                type: string
              creator_id:
                type: string
              quote_creator_id:
                type: string
              rfq_creator_id:
                type: string
              market_ticker:
                type: string
              event_ticker:
                type: string
              mve_collection_ticker:
                type: string
              mve_selected_legs:
                type: array
                items:
                  type: object
              contracts_fp:
                type: string
              target_cost_dollars:
                type: string
              rfq_target_cost_dollars:
                type: string
              yes_bid_dollars:
                type: string
              no_bid_dollars:
                type: string
              accepted_side:
                type: string
                enum: [yes, no]
              contracts_accepted_fp:
                type: string
              created_ts:
                type: integer
              deleted_ts:
                type: integer
              executed_ts:
                type: integer
    OrderGroupUpdates:
      name: OrderGroupUpdates
      title: Order Group Updates
      summary: Lifecycle and limit-tracking updates for order groups (authenticated).
      payload:
        type: object
        properties:
          type:
            type: string
            enum: [order_group_updates]
          sid:
            type: integer
          seq:
            type: integer
          msg:
            type: object
            properties:
              event_type:
                type: string
                enum: [created, triggered, reset, deleted, limit_updated]
              order_group_id:
                type: string
              contracts_limit_fp:
                type: string
              ts_ms:
                type: integer