Glossary · Technology & Connectivity
WebSocket API
Also: WebSocket, streaming API
Published
WebSocket API — A WebSocket API is a persistent, bidirectional connection over which a server pushes updates to a client as they occur, without the client polling. Digital asset liquidity providers and venues use WebSocket to stream executable prices, order book changes, and trade and order status in real time.
Push, Not Poll
A request-response API answers only when asked. A WebSocket connection stays open, and the server sends each price change or book update the moment it happens. For market data that changes many times a second, that is the difference between a current view and a stale one, and it removes the overhead of repeated requests.
What Streams Over WebSocket
Providers stream executable two-way prices at defined sizes, aggregated order book levels, trade prints, and updates on a client's own orders and fills. Clients subscribe to the channels they need. Because the connection is persistent, providers also use it for heartbeats that detect a dropped session quickly, which matters for a system that quotes or hedges against the feed.
Where It Fits
WebSocket carries the data a trading system watches continuously. Order entry and execution reporting from institutional systems typically go over FIX, and lower-frequency operations such as settlement instructions, balances, and reports go over REST. Many providers also accept orders over WebSocket for clients that prefer one connection.