Here you can find a basic, open source web based script to decode FIX messages. This tool was originally created as a PHP based service to help colleagues who frequently needed to read and understand these messages, often by digging through lengthy PDF specs to look up tag definitions. This tool streamlines that process by turning the raw FIX messages into readable tables with tag names and values. This version is built entirely using javascript without a backend.
In short, a FIX message represents a sequence of fields whose values are associated with unique numbers (tags). This method of communication is commonly used by brokerage firms and banks wishing to trade financial instruments on various stock exchanges of the world.
For further information, click here.
Disclaimer: The process takes place entirely within the browser. None of your FIX data is sent to the server. It was designed for a standard FIX 4.2/4.4 interpretation. Some exchanges e.g. EURONEXT use many custom non-standard tags.