Financial Modeling Prep WebSocket API

asyncapi: 3.0.0
info:
  title: Financial Modeling Prep WebSocket API
  version: stable
  description: Real-time market data streaming from Financial Modeling Prep. Authenticate with a login event carrying
    your API key, then subscribe to tickers or predefined market streams. Derived from the Websockets section of
    the official FMP API documentation (no provider-published AsyncAPI exists).
  externalDocs:
    url: https://site.financialmodelingprep.com/api-docs.md
    description: FMP API documentation, Websockets section
servers:
  standard:
    host: socket.financialmodelingprep.com
    protocol: wss
    description: Standard WebSocket server (login event with API key).
  socketio:
    host: socketio.financialmodelingprep.com
    protocol: wss
    description: Socket.IO server (same login/subscribe semantics over the Socket.IO protocol).
channels:
  stream:
    address: /
    description: 'Single duplex channel: send login/subscribe/unsubscribe events, receive login confirmations, quote
      updates, and heartbeats.'
    messages:
      login:
        $ref: '#/components/messages/login'
      subscribe:
        $ref: '#/components/messages/subscribe'
      unsubscribe:
        $ref: '#/components/messages/unsubscribe'
      loginResponse:
        $ref: '#/components/messages/loginResponse'
      quote:
        $ref: '#/components/messages/quote'
      heartbeat:
        $ref: '#/components/messages/heartbeat'
operations:
  sendLogin:
    action: send
    channel:
      $ref: '#/channels/stream'
    messages:
    - $ref: '#/channels/stream/messages/login'
    summary: Authenticate the session by sending your API key in a login event.
  sendSubscribe:
    action: send
    channel:
      $ref: '#/channels/stream'
    messages:
    - $ref: '#/channels/stream/messages/subscribe'
    summary: Subscribe to live price updates for tickers, or to a predefined market stream.
  sendUnsubscribe:
    action: send
    channel:
      $ref: '#/channels/stream'
    messages:
    - $ref: '#/channels/stream/messages/unsubscribe'
    summary: Stop receiving updates for a ticker or market stream.
  receiveQuote:
    action: receive
    channel:
      $ref: '#/channels/stream'
    messages:
    - $ref: '#/channels/stream/messages/quote'
    summary: Receive real-time quote updates for subscribed tickers/streams.
  receiveHeartbeat:
    action: receive
    channel:
      $ref: '#/channels/stream'
    messages:
    - $ref: '#/channels/stream/messages/heartbeat'
    summary: Regular heartbeat events signal an active connection; use to auto-reconnect.
components:
  messages:
    login:
      name: login
      summary: Authenticate with API key
      payload:
        type: object
        required:
        - event
        - data
        properties:
          event:
            const: login
          data:
            type: object
            properties:
              apiKey:
                type: string
    subscribe:
      name: subscribe
      summary: Subscribe to tickers (tickers) or a market stream (stream)
      payload:
        type: object
        required:
        - event
        properties:
          event:
            const: subscribe
          tickers:
            oneOf:
            - type: string
            - type: array
              items:
                type: string
            description: '"AAPL" or ["AAPL", "MSFT", "^GSPC"]'
          stream:
            type: string
            description: Exchange streams (nasdaq-basic-w-nls-plus, iex-tops, tsx-level-1, tsxv-level-1, lse-level-1,
              cboe-index-main), FMP streams (fmp-crypto-stream, fmp-index-stream, fmp-commodity-stream, fmp-currency-stream,
              fmp-us-equities-stream, fmp-us-otc-stream, fmp-uk-equities-stream, fmp-ca-equities-stream), or any
              stream with a -delayed suffix.
    unsubscribe:
      name: unsubscribe
      summary: Unsubscribe a ticker or market stream
      payload:
        type: object
        required:
        - event
        properties:
          event:
            const: unsubscribe
          ticker:
            oneOf:
            - type: string
            - type: array
              items:
                type: string
          stream:
            type: string
    loginResponse:
      name: loginResponse
      summary: Login confirmation
      payload:
        type: object
        properties:
          event:
            const: login
          data:
            type: object
            properties:
              status:
                type: integer
              message:
                type: string
        examples:
        - event: login
          data:
            status: 200
            message: Authenticated
    quote:
      name: quote
      summary: Real-time quote update
      payload:
        type: object
        description: Real-time quote update (fields from the documented example response).
        properties:
          symbol:
            type: string
          name:
            type: string
          price:
            type: number
          changesPercentage:
            type: number
          change:
            type: number
          dayLow:
            type: number
          dayHigh:
            type: number
          yearHigh:
            type: number
          yearLow:
            type: number
          marketCap:
            type:
            - number
            - 'null'
          priceAvg50:
            type: number
          priceAvg200:
            type: number
          exchange:
            type: string
          volume:
            type:
            - number
            - 'null'
          avgVolume:
            type:
            - number
            - 'null'
          open:
            type: number
          previousClose:
            type: number
          eps:
            type:
            - number
            - 'null'
          pe:
            type:
            - number
            - 'null'
          earningsAnnouncement:
            type:
            - string
            - 'null'
          sharesOutstanding:
            type:
            - number
            - 'null'
          timestamp:
            type: integer
    heartbeat:
      name: heartbeat
      summary: Connection heartbeat
      payload:
        type: object
        properties:
          event:
            const: heartbeat
          timestamp:
            type: integer
        examples:
        - event: heartbeat
          timestamp: 1747473420002
x-provenance:
  generated: '2026-07-22'
  method: derived
  source: https://site.financialmodelingprep.com/api-docs.md (Websockets section)