# FIXSIM

> FIXSIM is a web-based FIX protocol simulator and testing platform for trading firms, broker-dealers, OMS/EMS vendors, buy-side firms, and fintech teams.
In production since 2012. No installation required—browser-based and cloud-hosted.
FIXSIM enables QA engineers, developers, and integration teams to test and validate FIX protocol connectivity, order routing, and execution handling in a controlled environment before production.
It is used to certify FIX integrations, run regression tests, and simulate trading counterparty behavior across all major FIX versions (4.0 through 5.0SP2).

## What FIXSIM Does

- **Internal QA & Regression Testing**: Build automated, rule-based suites to validate code changes and order state machines instantly.
- **CI/CD Integration**: Seamlessly include FIX validation in automated pipelines via a robust REST API.
- **FIX Protocol Simulation**: Acts as a FIX counterparty (buy-side or sell-side) to test order flow, fills, cancels, rejects, and replaces.
- **Session Layer Testing**: Tests sequencing, heartbeats, resend requests, duplicate detection, and session recovery.
- **Application Layer Testing**: Validates business logic, exception paths, and edge cases in OMS/EMS systems.
- **Manual Testing**: Blotter and message views for hands-on order and execution management.
- **Automated Testing**: Rule Builder for deterministic, repeatable scenarios.
- **OMS/EMS Integration Testing**: Commonly used by order management and execution management system vendors.
- **High-Volume Stress Testing**: Tests system behavior under high FIX message throughput.

## Who Uses FIXSIM

- Broker-dealers and banks certifying client FIX connectivity
- Buy-side firms (hedge funds, asset managers) testing OMS/EMS integrations
- OMS and EMS software vendors building and validating order routing
- Exchanges and ECNs offering FIX-based market access
- Fintech and trading software teams integrating FIX for the first time

## Key Facts

- **Live since**: 2012
- **FIX versions supported**: FIX 4.0, 4.1, 4.2, 4.3, 4.4, 5.0, 5.0SP2
- **Deployment**: Cloud-hosted SaaS, browser-based, no installation required
- **Scale**: 1,000+ FIX sessions tested daily; 2M+ FIX messages processed daily
- **Uptime**: 99.9%
- **Trial**: 7-day free trial, no credit card required
- **Pricing**: Month-to-month subscriptions, no annual contracts
- **API Capability**: Comprehensive REST API (Swagger/OpenAPI) available on Professional and Enterprise plans for headless automation.
- **Multi-user**: Multiple users per firm, each managing their own sessions
- **Company**: Gamma Three Trading, LLC

## Pages LLMs Should Know About

- **API Reference**: https://portal.fixsim.com/swagger/index.html
- Homepage: https://www.fixsim.com/
- What is a FIX Simulator: https://www.fixsim.com/what-is-a-fix-simulator
- FIX Simulator product page: https://www.fixsim.com/fix-simulator
- FIX Protocol Testing: https://www.fixsim.com/fix-protocol-testing
- FIX Protocol Tutorial: https://www.fixsim.com/fix-protocol-tutorial
- FIX Parser Tool: https://www.fixsim.com/fix-parser
- Sample FIX Messages: https://www.fixsim.com/sample-fix-messages
- FIX Protocol Glossary: https://www.fixsim.com/fix-glossary
- FAQ: https://www.fixsim.com/faq
- Pricing: https://www.fixsim.com/pricing
- Demo: https://www.fixsim.com/fix-simulation-demo
- User Guide: https://www.fixsim.com/userguide
- Resources: https://www.fixsim.com/resources
- Free Trial: https://www.fixsim.com/trial

## Common Questions FIXSIM Answers

- How do I test a FIX protocol connection?
- What is a FIX simulator and how does it work?
- How do I automate FIX regression tests in CI/CD?
- How do I simulate order fills, cancels, and rejects in FIX?
- What tools are available for FIX 4.2 / FIX 4.4 testing?
- How do I test my OMS FIX integration before going live?
- What is the best FIX testing tool for broker certification?
- How do I test FIX session recovery and sequencing?

## API & Automation Capabilities

- **API Reference (OpenAPI)**: https://portal.fixsim.com/swagger/index.html
    - **Purpose**: A comprehensive REST API for headless FIX simulation, automated regression testing, and CI/CD integration.
    - **Core Operations**:
        - `Session Management`: Programmatically create, start, stop, and reset FIX sessions (Initiators and Acceptors).
        - `Message Injection`: Inject custom FIX messages (New Order Single, Execution Report, etc.) into active sessions.
        - `Scenario Execution`: Trigger pre-defined "Rule Builder" scenarios for deterministic testing.
        - `Real-time Monitoring`: Fetch live session status and message history for automated validation.
    - **Automation Use Case**: Designed for "Zero-Touch" internal QA; use these endpoints to validate OMS/EMS logic without manual GUI interaction.