Kraken Spot WebSocket API v2

asyncapi: 2.6.0
info:
  title: Kraken Spot WebSocket API v2
  version: '2.0.0'
  description: >
    Public WebSocket API for the Kraken cryptocurrency exchange (Spot v2).
    Provides real-time market data through subscribe/unsubscribe semantics over JSON.
    Channels documented here are restricted to the public surface confirmed by
    https://docs.kraken.com/api/docs/websocket-v2/ (ticker, book, ohlc, trade,
    instrument) plus the connection-level methods (ping/pong, subscribe,
    unsubscribe). Authenticated channels are intentionally out of scope.
  contact:
    name: Kraken API Support
    url: https://support.kraken.com/
  license:
    name: Kraken Terms of Service
    url: https://www.kraken.com/legal
defaultContentType: application/json

servers:
  public:
    url: ws.kraken.com/v2
    protocol: wss
    description: >
      Public market data WebSocket endpoint. No authentication required. Carries
      ticker, book, ohlc, trade, and instrument channels.
  authenticated:
    url: ws-auth.kraken.com/v2
    protocol: wss
    description: >
      Authenticated WebSocket endpoint used for private channels and trading
      methods (out of scope for this document; included here only because it is
      a documented separate host). Connecting requires a token obtained from the
      REST GetWebSocketsToken endpoint.

channels:
  ticker:
    description: >
      Level 1 market data: best bid/ask, last trade, 24h volume/VWAP/high/low,
      and price change metrics for one or more currency pairs.
    subscribe:
      summary: Receive ticker snapshot and updates from the server.
      message:
        oneOf:
          - $ref: '#/components/messages/TickerMessage'
          - $ref: '#/components/messages/SubscriptionStatus'
    publish:
      summary: Subscribe or unsubscribe from the ticker channel.
      message:
        oneOf:
          - $ref: '#/components/messages/SubscribeTicker'
          - $ref: '#/components/messages/UnsubscribeTicker'

  book:
    description: >
      Level 2 order book channel. Emits an initial snapshot of bids/asks
      followed by incremental updates. Includes a CRC32 checksum for the top
      10 levels.
    subscribe:
      summary: Receive book snapshot and update messages.
      message:
        oneOf:
          - $ref: '#/components/messages/BookMessage'
          - $ref: '#/components/messages/SubscriptionStatus'
    publish:
      summary: Subscribe or unsubscribe from the book channel.
      message:
        oneOf:
          - $ref: '#/components/messages/SubscribeBook'
          - $ref: '#/components/messages/UnsubscribeBook'

  ohlc:
    description: >
      Open/High/Low/Close candle data for a configured interval (1, 5, 15, 30,
      60, 240, 1440, 10080, or 21600 minutes). Updates are trade-triggered.
    subscribe:
      summary: Receive OHLC snapshot and update messages.
      message:
        oneOf:
          - $ref: '#/components/messages/OHLCMessage'
          - $ref: '#/components/messages/SubscriptionStatus'
    publish:
      summary: Subscribe or unsubscribe from the ohlc channel.
      message:
        oneOf:
          - $ref: '#/components/messages/SubscribeOHLC'
          - $ref: '#/components/messages/UnsubscribeOHLC'

  trade:
    description: >
      Stream of individual trade executions. Optional initial snapshot returns
      the most recent 50 trades for each subscribed symbol.
    subscribe:
      summary: Receive trade snapshot and update messages.
      message:
        oneOf:
          - $ref: '#/components/messages/TradeMessage'
          - $ref: '#/components/messages/SubscriptionStatus'
    publish:
      summary: Subscribe or unsubscribe from the trade channel.
      message:
        oneOf:
          - $ref: '#/components/messages/SubscribeTrade'
          - $ref: '#/components/messages/UnsubscribeTrade'

  instrument:
    description: >
      Reference data feed for all active assets and tradeable pairs, including
      precisions, trading limits, and margin parameters.
    subscribe:
      summary: Receive instrument snapshot and update messages.
      message:
        oneOf:
          - $ref: '#/components/messages/InstrumentMessage'
          - $ref: '#/components/messages/SubscriptionStatus'
    publish:
      summary: Subscribe or unsubscribe from the instrument channel.
      message:
        oneOf:
          - $ref: '#/components/messages/SubscribeInstrument'
          - $ref: '#/components/messages/UnsubscribeInstrument'

  ping:
    description: >
      Application-level keepalive. Distinct from the WebSocket protocol-level
      ping frames. Server replies with a pong message echoing req_id and
      including time_in/time_out timestamps.
    subscribe:
      summary: Receive pong response from the server.
      message:
        $ref: '#/components/messages/Pong'
    publish:
      summary: Send a ping to the server.
      message:
        $ref: '#/components/messages/Ping'

components:
  messages:
    SubscribeTicker:
      name: subscribeTicker
      title: Subscribe to ticker
      payload:
        $ref: '#/components/schemas/SubscribeTickerRequest'

    UnsubscribeTicker:
      name: unsubscribeTicker
      title: Unsubscribe from ticker
      payload:
        $ref: '#/components/schemas/UnsubscribeTickerRequest'

    TickerMessage:
      name: tickerMessage
      title: Ticker snapshot or update
      payload:
        $ref: '#/components/schemas/TickerEnvelope'

    SubscribeBook:
      name: subscribeBook
      title: Subscribe to book
      payload:
        $ref: '#/components/schemas/SubscribeBookRequest'

    UnsubscribeBook:
      name: unsubscribeBook
      title: Unsubscribe from book
      payload:
        $ref: '#/components/schemas/UnsubscribeBookRequest'

    BookMessage:
      name: bookMessage
      title: Book snapshot or update
      payload:
        $ref: '#/components/schemas/BookEnvelope'

    SubscribeOHLC:
      name: subscribeOHLC
      title: Subscribe to OHLC
      payload:
        $ref: '#/components/schemas/SubscribeOHLCRequest'

    UnsubscribeOHLC:
      name: unsubscribeOHLC
      title: Unsubscribe from OHLC
      payload:
        $ref: '#/components/schemas/UnsubscribeOHLCRequest'

    OHLCMessage:
      name: ohlcMessage
      title: OHLC snapshot or update
      payload:
        $ref: '#/components/schemas/OHLCEnvelope'

    SubscribeTrade:
      name: subscribeTrade
      title: Subscribe to trade
      payload:
        $ref: '#/components/schemas/SubscribeTradeRequest'

    UnsubscribeTrade:
      name: unsubscribeTrade
      title: Unsubscribe from trade
      payload:
        $ref: '#/components/schemas/UnsubscribeTradeRequest'

    TradeMessage:
      name: tradeMessage
      title: Trade snapshot or update
      payload:
        $ref: '#/components/schemas/TradeEnvelope'

    SubscribeInstrument:
      name: subscribeInstrument
      title: Subscribe to instrument
      payload:
        $ref: '#/components/schemas/SubscribeInstrumentRequest'

    UnsubscribeInstrument:
      name: unsubscribeInstrument
      title: Unsubscribe from instrument
      payload:
        $ref: '#/components/schemas/UnsubscribeInstrumentRequest'

    InstrumentMessage:
      name: instrumentMessage
      title: Instrument snapshot or update
      payload:
        $ref: '#/components/schemas/InstrumentEnvelope'

    SubscriptionStatus:
      name: subscriptionStatus
      title: Subscribe/Unsubscribe acknowledgement
      payload:
        $ref: '#/components/schemas/SubscriptionStatusResponse'

    Ping:
      name: ping
      title: Ping request
      payload:
        $ref: '#/components/schemas/PingRequest'

    Pong:
      name: pong
      title: Pong response
      payload:
        $ref: '#/components/schemas/PongResponse'

  schemas:

    # ---------- Common envelopes ----------

    SubscribeRequestBase:
      type: object
      required:
        - method
        - params
      properties:
        method:
          type: string
          enum: [subscribe]
        req_id:
          type: integer
          description: Optional client-originated request identifier echoed in the response.

    UnsubscribeRequestBase:
      type: object
      required:
        - method
        - params
      properties:
        method:
          type: string
          enum: [unsubscribe]
        req_id:
          type: integer

    SubscriptionStatusResponse:
      type: object
      description: Standard server acknowledgement for subscribe/unsubscribe requests.
      properties:
        method:
          type: string
          enum: [subscribe, unsubscribe]
        req_id:
          type: integer
        success:
          type: boolean
        result:
          type: object
          description: Echo of the parameters of a successful subscription.
        error:
          type: string
          description: Error message when success is false.
        time_in:
          type: string
          format: date-time
          description: RFC3339 timestamp the request was received on the wire.
        time_out:
          type: string
          format: date-time
          description: RFC3339 timestamp the response was sent on the wire.
        warnings:
          type: array
          items:
            type: string

    # ---------- Ticker ----------

    SubscribeTickerRequest:
      allOf:
        - $ref: '#/components/schemas/SubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [ticker]
                symbol:
                  type: array
                  items:
                    type: string
                  example: ["BTC/USD", "MATIC/GBP"]
                event_trigger:
                  type: string
                  enum: [bbo, trades]
                  default: trades
                  description: bbo emits on best-bid/offer change; trades emits on trade events.
                snapshot:
                  type: boolean
                  default: true

    UnsubscribeTickerRequest:
      allOf:
        - $ref: '#/components/schemas/UnsubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [ticker]
                symbol:
                  type: array
                  items:
                    type: string

    TickerEnvelope:
      type: object
      required: [channel, type, data]
      properties:
        channel:
          type: string
          enum: [ticker]
        type:
          type: string
          enum: [snapshot, update]
        data:
          type: array
          items:
            $ref: '#/components/schemas/Ticker'

    Ticker:
      type: object
      properties:
        symbol:
          type: string
        bid:
          type: number
          format: double
          description: Best bid price.
        bid_qty:
          type: number
          format: double
          description: Quantity at best bid.
        ask:
          type: number
          format: double
          description: Best ask price.
        ask_qty:
          type: number
          format: double
          description: Quantity at best ask.
        last:
          type: number
          format: double
          description: Last traded price.
        volume:
          type: number
          format: double
          description: 24-hour volume in the base currency.
        vwap:
          type: number
          format: double
          description: 24-hour volume weighted average price.
        low:
          type: number
          format: double
          description: 24-hour low price.
        high:
          type: number
          format: double
          description: 24-hour high price.
        change:
          type: number
          format: double
          description: 24-hour absolute price change.
        change_pct:
          type: number
          format: double
          description: 24-hour percentage price change.

    # ---------- Book ----------

    SubscribeBookRequest:
      allOf:
        - $ref: '#/components/schemas/SubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [book]
                symbol:
                  type: array
                  items:
                    type: string
                depth:
                  type: integer
                  enum: [10, 25, 100, 500, 1000]
                  default: 10
                snapshot:
                  type: boolean
                  default: true

    UnsubscribeBookRequest:
      allOf:
        - $ref: '#/components/schemas/UnsubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [book]
                symbol:
                  type: array
                  items:
                    type: string
                depth:
                  type: integer
                  enum: [10, 25, 100, 500, 1000]

    BookEnvelope:
      type: object
      required: [channel, type, data]
      properties:
        channel:
          type: string
          enum: [book]
        type:
          type: string
          enum: [snapshot, update]
        data:
          type: array
          items:
            $ref: '#/components/schemas/BookData'

    BookData:
      type: object
      properties:
        symbol:
          type: string
        bids:
          type: array
          items:
            $ref: '#/components/schemas/PriceLevel'
        asks:
          type: array
          items:
            $ref: '#/components/schemas/PriceLevel'
        checksum:
          type: integer
          format: int64
          description: CRC32 checksum of the top 10 bids and asks.
        timestamp:
          type: string
          format: date-time

    PriceLevel:
      type: object
      properties:
        price:
          type: number
          format: double
        qty:
          type: number
          format: double

    # ---------- OHLC ----------

    SubscribeOHLCRequest:
      allOf:
        - $ref: '#/components/schemas/SubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [ohlc]
                symbol:
                  type: array
                  items:
                    type: string
                interval:
                  type: integer
                  enum: [1, 5, 15, 30, 60, 240, 1440, 10080, 21600]
                snapshot:
                  type: boolean
                  default: true

    UnsubscribeOHLCRequest:
      allOf:
        - $ref: '#/components/schemas/UnsubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [ohlc]
                symbol:
                  type: array
                  items:
                    type: string
                interval:
                  type: integer
                  enum: [1, 5, 15, 30, 60, 240, 1440, 10080, 21600]

    OHLCEnvelope:
      type: object
      required: [channel, type, data]
      properties:
        channel:
          type: string
          enum: [ohlc]
        type:
          type: string
          enum: [snapshot, update]
        data:
          type: array
          items:
            $ref: '#/components/schemas/Candle'

    Candle:
      type: object
      properties:
        symbol:
          type: string
        open:
          type: number
          format: double
        high:
          type: number
          format: double
        low:
          type: number
          format: double
        close:
          type: number
          format: double
        vwap:
          type: number
          format: double
        trades:
          type: integer
          description: Number of trades in the interval.
        volume:
          type: number
          format: double
          description: Total traded volume in the base currency.
        interval_begin:
          type: string
          format: date-time
          description: RFC3339 timestamp of interval start.
        interval:
          type: integer
          description: Interval length in minutes.

    # ---------- Trade ----------

    SubscribeTradeRequest:
      allOf:
        - $ref: '#/components/schemas/SubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [trade]
                symbol:
                  type: array
                  items:
                    type: string
                snapshot:
                  type: boolean
                  default: false
                  description: When true, returns the most recent 50 trades on subscribe.

    UnsubscribeTradeRequest:
      allOf:
        - $ref: '#/components/schemas/UnsubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel, symbol]
              properties:
                channel:
                  type: string
                  enum: [trade]
                symbol:
                  type: array
                  items:
                    type: string

    TradeEnvelope:
      type: object
      required: [channel, type, data]
      properties:
        channel:
          type: string
          enum: [trade]
        type:
          type: string
          enum: [snapshot, update]
        data:
          type: array
          items:
            $ref: '#/components/schemas/Trade'

    Trade:
      type: object
      properties:
        symbol:
          type: string
        side:
          type: string
          enum: [buy, sell]
          description: Taker order direction.
        qty:
          type: number
          format: double
        price:
          type: number
          format: double
        ord_type:
          type: string
          enum: [limit, market]
          description: Taker order type.
        trade_id:
          type: integer
          format: int64
          description: Sequence number unique per trading book.
        timestamp:
          type: string
          format: date-time

    # ---------- Instrument ----------

    SubscribeInstrumentRequest:
      allOf:
        - $ref: '#/components/schemas/SubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel]
              properties:
                channel:
                  type: string
                  enum: [instrument]
                execution_venue:
                  type: string
                  enum: [international, bitnomial-exchange]
                  default: international
                include_tokenized_assets:
                  type: boolean
                  default: false
                snapshot:
                  type: boolean
                  default: true

    UnsubscribeInstrumentRequest:
      allOf:
        - $ref: '#/components/schemas/UnsubscribeRequestBase'
        - type: object
          properties:
            params:
              type: object
              required: [channel]
              properties:
                channel:
                  type: string
                  enum: [instrument]

    InstrumentEnvelope:
      type: object
      required: [channel, type, data]
      properties:
        channel:
          type: string
          enum: [instrument]
        type:
          type: string
          enum: [snapshot, update]
        data:
          type: object
          properties:
            assets:
              type: array
              items:
                $ref: '#/components/schemas/Asset'
            pairs:
              type: array
              items:
                $ref: '#/components/schemas/Pair'

    Asset:
      type: object
      properties:
        id:
          type: string
        status:
          type: string
        precision:
          type: integer
        precision_display:
          type: integer
        borrowable:
          type: boolean
        collateral_value:
          type: number
          format: double
        margin_rate:
          type: number
          format: double
        multiplier:
          type: number
          format: double

    Pair:
      type: object
      properties:
        symbol:
          type: string
        base:
          type: string
        quote:
          type: string
        status:
          type: string
        marginable:
          type: boolean
        has_index:
          type: boolean
        qty_min:
          type: string
        qty_increment:
          type: string
        qty_precision:
          type: integer
        price_increment:
          type: string
        price_precision:
          type: integer
        cost_precision:
          type: integer
        cost_min:
          type: string
        margin_initial:
          type: number
          format: double
        position_limit_long:
          type: integer
        position_limit_short:
          type: integer

    # ---------- Ping / Pong ----------

    PingRequest:
      type: object
      required: [method]
      properties:
        method:
          type: string
          enum: [ping]
        req_id:
          type: integer

    PongResponse:
      type: object
      required: [method]
      properties:
        method:
          type: string
          enum: [pong]
        req_id:
          type: integer
        success:
          type: boolean
        time_in:
          type: string
          format: date-time
        time_out:
          type: string
          format: date-time
        result:
          type: object
        error:
          type: string
        warnings:
          type: array
          items:
            type: string