/
FIX Client Simulator User Guide

FIX Client Simulator User Guide

Jan 23, 2026

Product Overview

EPAM B2BITS FIX Client Simulator (FCS) is a rich desktop UI application. It allows to simulate multiple FIX protocol-defined buy-side- and sell-side-oriented workflows and create repeatable test scenarios for FIX sessions. FCS combines the ability to generate, manually enter, and edit FIX messages in row format and via pre-defined forms. It allows to assemble and replay FIX messages in a highly automated fashion with automatic handling of sequence numbers and identities.

FCS is used in the following use cases:

  • OMS/EMS functional and stress testing

  • Automated FIX integration testing 

  • FIX protocol implementations

  • Errors reproducing

FCS covers all spectrum of FIX protocol versions and supports custom extensions and QuickFIX-formatted dictionaries.

FIX Client Simulator features

  • Establishing multiple acceptor and/or initiator sessions on local and/or remote hosts

  • Support of unregistered acceptor sessions

  • Restarting the working session with or without session logs restoration

  • Restoring session state and configurations on FCS startup

  • Support of all FIX message types (pre-trade, trade, post-trade, market data, etc.)

  • Standard 4.0 - FIXLatest FIX application versions support

  • Custom dictionaries support

  • Overriding SenderCompID and TargetCompID for the established session

  • Manual sequence numbers definition or reset

  • Validation of incoming and outgoing FIX and QuickFIX messages 

  • Wide range of FIX session settings including Custom Logon message

  • Replaying selected log files

  • Ability to load, modify, and send a file containing a preset message or batch of messages

  • Enabling/disabling message re-sending

  • Sending messages in a defined interval

  • Tag values autoincrement

  • Events monitoring:

    • sent and received messages

    • session states

  • Creating, recording, editing, and running test scenarios for FIX sessions

Prerequisites and System Requirements

FIX Client Simulator is based on FIX Antenna C/C++/.NET FIX Engine. It can be installed separately or as a part of the FIX Antenna .NET package.  

  • Any modern Intel-based server or workstation with a 64-bit CPU can be used as hardware.

  • Supported operating systems:

    • Windows 7

    • Windows 8

    • Windows 10

    • Windows 11

    • Windows Server 2008 R2

    • Windows Server 2012

    • Windows Server 2016

    • Ubuntu Linux 20.04

    • Ubuntu Linux 22.04

    • Rocky Linux 8

    • macOS

  • (For Windows users only) Latest (14.42.34438.0) Microsoft Visual C++ Redistributable Package (x64) should be installed before the FIX Client Simulator's installation.

  • (For Linux and macOS users only) Download and install Wine from the official site to run the FIX Client Simulator.

Installation on Linux Mint and Ubuntu

FCS has been available on Linux since the FIX Client Simulator 3.5.0 release.

To install FIX Client Simulator on Linux Mint and Ubuntu follow the instructions below:

  1. Install Wine (instruction for Ubuntu and Mint).

  2. Install Winetricks using the following commands:

    sudo apt install winetricks

  3. Install .NET Framework 4.8 using the following commands: 

    winetricks --force dotnet48 winetricks --force corefonts

    If Wine prompts for installing Mono, click Cancel. Please refer to the HowTo section for more details.

  4. Navigate to the FCS folder and run it.

    cd ./FCS_<version> wine Fcs.exe

Installation on macOS

FCS has been available on macOS since the FIX Client Simulator 3.5.0 release.

To install FIX Client Simulator on macOS follow the instructions below:

  1. Install Wine

    1. Option 1 - Download and install Wine from the official site

    2. Option 2 - Download and install Wine using Brew

      brew install --cask wine-stable

  2. Navigate to the FCS folder and run it.

    1. Option 1 - via Terminal

      cd ./FCS_<version> wine Fcs.exe

    2. Option 2 - via context menu