But this doesn’t work for “push” notifications such as market data, or notifications of a trade after a period of delay. The REST portion is essentially a “request-response” interaction I send you a request (get or post), and you respond with a one-time response back. Well, the first (and perhaps) biggest thing to note is that I’m referring to REST and Websocket here you need both in combination with web APIs to achieve the type of communication you need for trading. So what’s the difference between FIX and REST/Websocket? Its strengths lie in the fact that it covers all asset classes and the organisation behind it - the FIX Trading Community - have modelled more and more workflows in it over the years, including order delivery and execution, quoting, market data, and even into after-the-trade activities such as settlement.įIX really was well ahead of its time when it was first launched, and while it has a learning curve to it, it is simple and robust enough that it is still really well-suited to the job today, thanks to the fact that it is very efficient and it is extremely well-supported. I’ll assume here that if you are reading this, you know probably know more about REST/Websocket APIs than FIX APIs because it’s quite an old and specialist protocol.įIX was originally launched in the early 90s (a time before the modern internet!) and has grown to dominate institutional market connectivity within trading it’s the protocol that the vast majority of investment banks and brokers use to “talk” both to each other and to trading venues. You might be asking why have both, and what’s the difference between them?

One of the trends that we are seeing with more recent trading venues (which tend to be crypto exchanges), is that they are starting to offer both REST/Websocket and FIX interfaces.

Api vs rest api