AsyncAPI channel · CoinAPI · CoinAPI Market Data WebSocket API

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Single WebSocket channel. The client publishes control messages (`hello`, `subscribe`, `unsubscribe`) and the server publishes market data messages (`trade`, `quote`, `book`, `book5`, `book20`, `book50`, `book_l3`, `ohlcv`, `exrate`, `asset`, `exchange`, `symbol`) plus control messages (`reconnect`, `heartbeat`, `error`).

Open source AsyncAPI → All CoinAPI channels CoinAPI provider profile
Provider: CoinAPI AsyncAPI: v2.6.0 Spec: CoinAPI Market Data WebSocket API Operations: 2 Messages: 18

Channel address

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Operations

publish
clientToServer
Messages sent by the client to CoinAPI.
serverToClient
Messages streamed by CoinAPI to the client.

Messages

hello
Initial handshake / subscription override message. Required after the WebSocket connection is opened. May be repeated to replace the entire subscription scope. Carries the API key, heartbeat preferenc
Content-Type: application/json
subscribe
Adds data types and/or filters to the existing subscription scope without discarding prior subscriptions.
Content-Type: application/json
unsubscribe
Removes specific data types and/or filters from the current subscription scope. Other subscriptions remain active.
Content-Type: application/json
trade
Sent for every executed transaction (order book match).
Content-Type: application/json
quote
Sent for each update on the best bid or ask level.
Content-Type: application/json
book
Full order book snapshot and real-time updates (level 2, aggregated by price level).
Content-Type: application/json
book5
First 5 best bid and ask levels.
Content-Type: application/json
book20
First 20 best bid and ask levels.
Content-Type: application/json
book50
First 50 best bid and ask levels.
Content-Type: application/json
book_l3
Level 3 (order-by-order) book snapshot and updates. Each entry is a passive order with id, price, size, and update_type.
Content-Type: application/json
ohlcv
OHLCV bar updates between 1SEC and 1DAY periods; emitted when a period closes or every ~5 seconds during an open period.
Content-Type: application/json
exrate
Rolling 24-hour Volume Weighted Average Price across selected data sources for a base/quote asset pair.
Content-Type: application/json
asset
Asset metadata snapshot and periodic updates (volumes, USD price, data coverage ranges).
Content-Type: application/json
exchange
Exchange metadata snapshot and periodic updates (data coverage, symbols count, website).
Content-Type: application/json
symbol
Symbol metadata snapshot and periodic updates (volume, price, precision, data coverage).
Content-Type: application/json
reconnect
Sent before a planned server restart or shutdown so clients can gracefully reconnect within the indicated window.
Content-Type: application/json
heartbeat
Sent every second of silence in the data stream when the client opted in via `heartbeat: true` in the Hello/Subscribe message.
Content-Type: application/json
error
Permanent error notice. The server closes the underlying WebSocket connection after sending this message.
Content-Type: application/json

About AsyncAPI

The AsyncAPI specification describes event-driven APIs the way OpenAPI describes request/response APIs. A channel is the named pipe — a webhook URL, a Kafka topic, a WebSocket route, an MQTT subject — that producers and consumers publish or subscribe to. Each channel carries one or more messages with structured payloads, and an operation declares whether a given party sends or receives on that channel.

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