FIXSIM User Guide

FIXSIM is a browser-based FIX Protocol testing and simulation platform used by QA engineers, developers, and integration teams at broker-dealers, OMS/EMS vendors, buy-side firms, and fintech companies worldwide.

Whether you are developing a new Order Management System (OMS) or Execution Management System (EMS), integrating with a broker-dealer, or certifying an exchange API, FIXSIM provides a high-performance FIX testing environment accessible entirely from your browser, with no local installations required.

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What You'll Find in This Guide

• Getting Started - Connect your FIX engine to FIXSIM for the first time.
• FIX Sessions - Create and manage FIX initiator and acceptor sessions.
• Configuring Sessions - Mirror your production FIX session settings.
• Sending & Receiving Messages - Send FIX flows and inspect FIXSIM responses.
• Session Views - Monitor real-time message flows and session state.
• Reports Overview - Understand FIXSIM reporting and blotter views.
• Blotter In - View inbound orders and executions.
• Blotter Out - View outbound orders and execution reports.
• Custom Tags - Configure and apply custom FIX tags to your sessions.
• FIX Session Settings - Detailed session configuration reference.
• App Settings - Manage application-level settings and preferences.
• Log Replay - Upload and replay FIX log files, view replay stats, and download session logs.
• Rules & Automation - Build automated FIX test scenarios with the Rule Builder.
• Securities - Define symbols, identifiers, and the prices that drive executions and market data.
• Algo Tickets (FIXatdl) - Upload broker FIXatdl files and send algo orders from rendered tickets.
• REST API - Drive sessions, orders, executions, and raw message injection programmatically.
• DK Trades - Test Don't Know Trade (35=Q) handling in both directions.
• Managing Users & Roles - Invite teammates and control roles, instance access, and seats.
• Single Sign-On (SSO) - Connect Microsoft Entra ID, Okta, or any OpenID Connect provider and roll SSO out to your team (Enterprise).
• Troubleshooting - Resolve common FIX connection and sequence issues.
• Reference - Links to FIX tutorials, sample messages, and glossary.

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New to FIXSIM?

Start with the Getting Started guide to connect your first FIX session. For a broader introduction to FIX protocol testing, see What is a FIX Simulator or explore the FIX Protocol Resources library.