FIX Standards

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FIX Trading Community™ activities span a wide range of technical capabilities and disciplines impacting every aspect of electronic trading and the trade life-cycle. This is the place to find the specifications and resources to help you effectively understand and use the various FIX standards.

FIX Family of Standards

Application Level

FIX currently supports three versions of the application messages that serve as the basis for standardization and automation of the electronic trading industry.

Version 5.0 Service Pack 2
The most current version of FIX that supports multiple asset classes and a wide range of trading life cycle business processes. Originally released in 2009 there have been a considerable number of extension packs created for FIX.5.0SP2. The FIX session protocol was separated from the application with the introduction of FIX.5.0
FIX employs a process of Extension Packs to add new functionality to the standard. There have been over 200 Extension Packs created for the FIX standard.

Version 4.4
FIX.4.4 is one of the most widely adopted versions oF FIX. FIX.4.4 covers multiple asset classes including fixed income instruments. As of 2010, it is considered compliant to use fields, messages, and components as of the latest extension pack of FIX with FIX.4.4.

Version 4.2
FIX.4.2 is widely used for equities, FX, and listed derivatives trading.

FIX Algorithmic Trading Definition Language (FIXatdl) – is an XML based standard to specify the user interface components for algorithmic trading.

User Defined Fields
The table on this page summarizes currently used custom fields.  At this time, the available tag numbers in the user defined range of 5000 to 9999 have all been allocated.

FIX supports external code lists for certain fields.

Unsupported Application Versions
The FIX Community discontinued support for earlier versions of FIX. The specifications are maintained on the website for these unsupported versions.


FIX supports multiple encodings to support a variety of uses and industry technology standards.

tagvalue (classic FIX)
The FIX Tag=Value encoding is the original encoding and the most widely used encoding. A simple ASCII string format.

FIXML is the XML encoding used within FIX. FIXML is widely adopted for derivatives post trade clearing and settlement globally. FIXML is also used for reporting.

Simple Binary Encoding (SBE)
SBE is a high performance binary encoding in use within the industry for market data dissemination. SBE was developed within the High Performance Working Group.

Google Protocol Buffers (GPB)
GPB is an encoding using Google Protocol Buffers. GPB encodings of FIX are often used within companies as part of internal message.

Javascript Object Notation (JSON)
Still under development and available as a release candidate, the JSON encoding is intended for both internal processing and the use of FIX application messages within web based applications and APIs.

Abstract Syntax Notation (ASN.1)
ASN.1 is an ISO standard encoding system that includes multiple encodings itself. ASN.1 support was added as part of the work of the High Performance Working Group.

FIX Adapted for Streaming (FAST)
FAST is a protocol designed to reduce bandwidth use and latency for market data dissemination.

Session Protocols

The FIX Session Layer is widely adopted to provide reliable, ordered, recoverable communication between market participants.

FIX4 Session Protocol for Version 4.2 and Version 4.4
FIX4 is the most widely adopted session layer. Within FIX.4.2 and  FIX.4.4 the session layers are included as part of the application layer.

FIX Transport Session Protocol (FIXT)
Beginning with the FIX.5.0 version the session layer was separated from the application layer. FIXT as it is called is the application version independent session layer that is used in conjunction with FIX.5.0SP2 and later versions of FIX.

FIX High Performance Session Layer (FIXP)
FIXP is the new high performance session layer that supports multiple modes of operation.

FIX Simple Open Framing Header (SOFH)
A simple and primitive message framing header that communicates two pieces of information, the length of a message and the encoding type of that message.

FIXS is the standard to secure FIX sessions using the Transport Layer Security (TLS) protocol.

Resources to help you use the FIX Standards

FIX Orchestra and Repository

The FIX Repository is a set of XML files for the FIX Protocol application layer messaging specification. FIX Orchestra is a current initiative to facilitate machine readable rules of engagement between counterparties.

Get Repository


FIXimate is the web-based view of the FIX Protocol component, message and data dictionary definitions, covering versions 4.0 to 5.0SP2. A link is also provided to the FIXimate for the latest available Extension Pack (EP).

Search FIXimate


The FIXwiki provides a wiki platform in which members can share their knowledge and implementation know-how of the FIX Protocol standard. You must be a member in order to obtain a login to edit the FIXwiki.

Open FIXWiki

FIX Trading Community would like to thank AtlassianAltova and NoMagic, Inc. for kindly contributing complementary licenses of their design tools which will enable FIX Trading Community to focus on its core business of creating industry standards and will help in our technical efforts by further automating the maintenance of FIX messaging standards.