Capital.com WebSocket API

asyncapi: '2.6.0'
info:
  title: Capital.com WebSocket Streaming API
  version: '1.0.0'
  description: |
    Real-time streaming API from Capital.com for market data and OHLC candlestick updates.
    Clients connect over WebSocket using session tokens (CST and X-SECURITY-TOKEN) obtained
    from the Capital.com REST API. A single connection supports up to 40 concurrent instrument
    subscriptions and must be pinged at least once every 10 minutes to remain active.
  contact:
    name: Capital.com API Support
    url: https://open-api.capital.com
  termsOfService: https://capital.com/terms-and-conditions
  license:
    name: Capital.com Terms of Service
    url: https://capital.com/terms-and-conditions

servers:
  production:
    url: api-streaming-capital.backend-capital.com/connect
    protocol: wss
    description: Capital.com production WebSocket streaming endpoint.
  demo:
    url: demo-api-streaming-capital.backend-capital.com/connect
    protocol: wss
    description: Capital.com demo WebSocket streaming endpoint.

defaultContentType: application/json

channels:
  /:
    description: |
      Single WebSocket channel for all destinations. Clients send frames whose `destination`
      field selects an operation (marketData.subscribe, marketData.unsubscribe,
      OHLCMarketData.subscribe, OHLCMarketData.unsubscribe, ping). The server publishes
      subscription confirmations, market data updates, OHLC bar updates, and ping responses
      on the same connection.
    publish:
      operationId: sendClientFrame
      summary: Frames sent from the client to Capital.com.
      message:
        oneOf:
          - $ref: '#/components/messages/MarketDataSubscribe'
          - $ref: '#/components/messages/MarketDataUnsubscribe'
          - $ref: '#/components/messages/OHLCMarketDataSubscribe'
          - $ref: '#/components/messages/OHLCMarketDataUnsubscribe'
          - $ref: '#/components/messages/Ping'
    subscribe:
      operationId: receiveServerFrame
      summary: Frames received from Capital.com.
      message:
        oneOf:
          - $ref: '#/components/messages/SubscriptionStatus'
          - $ref: '#/components/messages/MarketDataUpdate'
          - $ref: '#/components/messages/OHLCMarketDataUpdate'
          - $ref: '#/components/messages/PingResponse'

components:
  messages:
    MarketDataSubscribe:
      name: marketDataSubscribe
      title: Subscribe to real-time market data
      summary: Subscribe to live bid/offer price updates for a set of instrument epics.
      payload:
        $ref: '#/components/schemas/MarketDataSubscribeFrame'

    MarketDataUnsubscribe:
      name: marketDataUnsubscribe
      title: Unsubscribe from real-time market data
      summary: Remove real-time price subscriptions for one or more epics.
      payload:
        $ref: '#/components/schemas/MarketDataUnsubscribeFrame'

    OHLCMarketDataSubscribe:
      name: ohlcMarketDataSubscribe
      title: Subscribe to OHLC candlestick updates
      summary: Subscribe to OHLC candle updates for a set of epics, resolutions, and bar type.
      payload:
        $ref: '#/components/schemas/OHLCMarketDataSubscribeFrame'

    OHLCMarketDataUnsubscribe:
      name: ohlcMarketDataUnsubscribe
      title: Unsubscribe from OHLC candlestick updates
      summary: Remove OHLC subscriptions for the given epics, with optional resolution and type filters.
      payload:
        $ref: '#/components/schemas/OHLCMarketDataUnsubscribeFrame'

    Ping:
      name: ping
      title: Ping the streaming session
      summary: Keep the WebSocket session alive (must be sent at least every 10 minutes).
      payload:
        $ref: '#/components/schemas/PingFrame'

    SubscriptionStatus:
      name: subscriptionStatus
      title: Subscription processing status
      summary: Confirms processing status of a subscribe or unsubscribe request per epic.
      payload:
        $ref: '#/components/schemas/SubscriptionStatusFrame'

    MarketDataUpdate:
      name: marketDataUpdate
      title: Real-time market data update
      summary: Streaming bid/offer quote update for a subscribed instrument.
      payload:
        $ref: '#/components/schemas/MarketDataUpdateFrame'

    OHLCMarketDataUpdate:
      name: ohlcMarketDataUpdate
      title: OHLC candlestick update
      summary: Streaming OHLC bar update for a subscribed instrument and resolution.
      payload:
        $ref: '#/components/schemas/OHLCMarketDataUpdateFrame'

    PingResponse:
      name: pingResponse
      title: Ping response
      summary: Server acknowledgement of a client ping.
      payload:
        $ref: '#/components/schemas/PingResponseFrame'

  schemas:
    MarketDataSubscribeFrame:
      type: object
      required:
        - destination
        - correlationId
        - cst
        - securityToken
        - payload
      properties:
        destination:
          type: string
          enum:
            - marketData.subscribe
        correlationId:
          type: string
          description: Client-generated id to correlate request and response frames.
          example: '1'
        cst:
          type: string
          description: CST access token from a REST API session.
        securityToken:
          type: string
          description: X-SECURITY-TOKEN account identifier from a REST API session.
        payload:
          type: object
          required:
            - epics
          properties:
            epics:
              type: array
              description: List of instrument epics to subscribe to (up to 40 concurrent).
              maxItems: 40
              items:
                type: string
              example:
                - OIL_CRUDE
                - AAPL

    MarketDataUnsubscribeFrame:
      type: object
      required:
        - destination
        - correlationId
        - cst
        - securityToken
        - payload
      properties:
        destination:
          type: string
          enum:
            - marketData.unsubscribe
        correlationId:
          type: string
          example: '2'
        cst:
          type: string
        securityToken:
          type: string
        payload:
          type: object
          required:
            - epics
          properties:
            epics:
              type: array
              items:
                type: string
              example:
                - OIL_CRUDE

    OHLCMarketDataSubscribeFrame:
      type: object
      required:
        - destination
        - correlationId
        - cst
        - securityToken
        - payload
      properties:
        destination:
          type: string
          enum:
            - OHLCMarketData.subscribe
        correlationId:
          type: string
          example: '3'
        cst:
          type: string
        securityToken:
          type: string
        payload:
          type: object
          required:
            - epics
          properties:
            epics:
              type: array
              description: Up to 40 instrument epics.
              maxItems: 40
              items:
                type: string
              example:
                - AAPL
            resolutions:
              type: array
              description: Candle timeframes to subscribe to. Defaults to MINUTE.
              items:
                type: string
                enum:
                  - MINUTE
                  - MINUTE_5
                  - MINUTE_15
                  - MINUTE_30
                  - HOUR
                  - HOUR_4
                  - DAY
                  - WEEK
              example:
                - MINUTE_5
            type:
              type: string
              description: Candle bar format. Defaults to classic.
              enum:
                - classic
                - heikin-ashi
              default: classic

    OHLCMarketDataUnsubscribeFrame:
      type: object
      required:
        - destination
        - correlationId
        - cst
        - securityToken
        - payload
      properties:
        destination:
          type: string
          enum:
            - OHLCMarketData.unsubscribe
        correlationId:
          type: string
          example: '4'
        cst:
          type: string
        securityToken:
          type: string
        payload:
          type: object
          required:
            - epics
          properties:
            epics:
              type: array
              items:
                type: string
              example:
                - AAPL
            resolutions:
              type: array
              description: Optional resolutions to unsubscribe from. Defaults to all.
              items:
                type: string
                enum:
                  - MINUTE
                  - MINUTE_5
                  - MINUTE_15
                  - MINUTE_30
                  - HOUR
                  - HOUR_4
                  - DAY
                  - WEEK
            types:
              type: array
              description: Optional candle types to unsubscribe from. Defaults to all.
              items:
                type: string
                enum:
                  - classic
                  - heikin-ashi

    PingFrame:
      type: object
      required:
        - destination
        - correlationId
        - cst
        - securityToken
      properties:
        destination:
          type: string
          enum:
            - ping
        correlationId:
          type: string
          example: '5'
        cst:
          type: string
        securityToken:
          type: string

    SubscriptionStatusFrame:
      type: object
      description: |
        Frame returned in response to marketData.subscribe, marketData.unsubscribe,
        OHLCMarketData.subscribe, or OHLCMarketData.unsubscribe.
      properties:
        status:
          type: string
          description: Overall status of the request (for example, OK).
          example: OK
        destination:
          type: string
          example: marketData.subscribe
        correlationId:
          type: string
          example: '1'
        payload:
          type: object
          properties:
            subscriptions:
              type: object
              additionalProperties:
                type: string
                description: Per-epic subscription processing status (for example, PROCESSED).
                example: PROCESSED

    MarketDataUpdateFrame:
      type: object
      description: Streaming market data quote frame.
      properties:
        status:
          type: string
          example: OK
        destination:
          type: string
          enum:
            - quote
        payload:
          type: object
          properties:
            epic:
              type: string
              description: Instrument identifier.
              example: OIL_CRUDE
            product:
              type: string
              description: Instrument category (for example, CFD).
              example: CFD
            bid:
              type: number
              format: double
              description: Current bid price.
            bidQty:
              type: number
              format: double
              description: Quantity available at the current bid.
            ofr:
              type: number
              format: double
              description: Current offer (ask) price.
            ofrQty:
              type: number
              format: double
              description: Quantity available at the current offer.
            timestamp:
              type: integer
              format: int64
              description: Update timestamp in milliseconds since epoch.

    OHLCMarketDataUpdateFrame:
      type: object
      description: Streaming OHLC candle update frame.
      properties:
        status:
          type: string
          example: OK
        destination:
          type: string
          enum:
            - ohlc.event
        payload:
          type: object
          properties:
            epic:
              type: string
              example: AAPL
            resolution:
              type: string
              enum:
                - MINUTE
                - MINUTE_5
                - MINUTE_15
                - MINUTE_30
                - HOUR
                - HOUR_4
                - DAY
                - WEEK
            type:
              type: string
              enum:
                - classic
                - heikin-ashi
            priceType:
              type: string
              description: Price basis used to build the candle.
              enum:
                - bid
                - ask
            t:
              type: integer
              format: int64
              description: Bar timestamp in milliseconds since epoch.
            o:
              type: number
              format: double
              description: Opening price of the bar.
            h:
              type: number
              format: double
              description: Highest price of the bar.
            l:
              type: number
              format: double
              description: Lowest price of the bar.
            c:
              type: number
              format: double
              description: Closing price of the bar.

    PingResponseFrame:
      type: object
      properties:
        status:
          type: string
          example: OK
        destination:
          type: string
          enum:
            - ping
        correlationId:
          type: string
          example: '5'
        payload:
          type: object
          description: Empty payload.