FIX is an institutional protocol family
FIX connections normally include session state, heartbeats, sequence numbers, logon behaviour and message types agreed with a counterparty. Market data may arrive through snapshots, incremental refreshes or implementation-specific workflows. A FIX integration should be engineered against the actual counterparty specification rather than a generic assumption.
WebSocket is convenient for application streaming
WebSocket creates a persistent bidirectional connection that fits browser, mobile and server applications. The protocol itself does not define market-data semantics, so the API must specify subscription messages, snapshots, incremental updates, timestamps, reconnect behaviour and versioning.
Recovery behaviour is different
FIX session recovery can involve sequence management and counterparty rules. WebSocket recovery is usually application-defined: reconnect, authenticate again if required, resubscribe and obtain a fresh snapshot. In both cases, consuming applications need deterministic state reconstruction.
They often coexist
A broker may receive data from an institutional source over FIX and redistribute normalized prices to internal or client applications over WebSocket. This is one reason to normalize the feed before distribution rather than exposing upstream protocol assumptions directly to every consumer.
Choose by role, not by marketing label
Use the protocol that matches the technical and commercial role. FIX can be appropriate for institutional source connectivity or trading infrastructure; WebSocket is often appropriate for real-time application delivery. REST can complement either one for snapshots, metadata and historical retrieval.
How this applies to a broker deployment
The exact architecture depends on the selected sources, instruments, platform, regions, data rights and operating model. PriceFeed.xyz scopes those requirements before defining a production design. The examples in this guide explain engineering concepts and do not imply a specific source entitlement, hosting location, latency guarantee or service-level commitment.