Senior Staff Engineer/ .Net Developer with FIX Knowledge

Overview

With 4,300 employees and over 400,000 retail and institutional clients from more than 80 offices spread across five continents, we’re a Fortune-100, Nasdaq-listed provider, connecting clients to the global markets – focusing on innovation, human connection, and providing world-class products and services to all types of investors.

At StoneX, we offer you the opportunity to be part of an institutional-grade financial services network that connects companies, organizations, and investors to the global markets ecosystem. As a team member, you'll benefit from our unique blend of digital platforms, comprehensive clearing and execution services, personalized high-touch support, and deep industry expertise. Elevate your career with us and make a significant impact in the world of global finance.

Working across institutional and retail clients, immerse yourself in the best-in-class institutional-grade technology, working alongside industry experts and gaining exposure to various asset classes, such as equities, options, fixed income securities, and advanced trading, research, and management technology. Empower individual investors – and yourself – in the world of retail through a range of different financial products rooted in innovation and market intelligence. From FX and CFDs to precious metals, master an exciting world of wealth management tools.

Responsibilities

Position Purpose: This role exists to establish and maintain the critical connectivity layer that binds essential trading and pricing systems, ensuring seamless real-time data exchanges across our platforms. It underpins our technology strategy by guaranteeing that our communication infrastructure—from FIX connectivity to the messaging backbone—remains robust, scalable, and capable of driving operational excellence and innovation. With focus on retail FIX engines modernization, you will be instrumental in assuring StoneX partners seamless transition to Nexus platform. You will also help team in payments, institutional and trade processing space to deliver FIX related projects.

Technology Ecosystem: This role operates within a robust technology ecosystem where, sitting among mature .net retail-based systems, it focuses modernization and refining into mission-critical FIX connectivity and integration services. Leveraging Azure as our cloud backbone, the position is central to ensuring seamless, high-performance communication across distributed systems—including messaging platforms like Apache MQ Artemis, Kafka, and RedPanda—while embracing principles of multithreading and mechanical sympathy.

Primary duties will include:

• Modernize mature .net FIX engines : Design, implement, and continuously refine the high-performance FIX connectivity layer to ensure secure and reliable communication between trading systems. Remove outdated dependencies, containerize, enable smooth Nexus transition.
• Build Integration Services and Middleware : Assure robust FIX integration and seamless connectivity with the TREP pricing platform and messaging backbones Apache MQ Artemis, Kafka (RedPanda) to facilitate real-time data flows.
• Optimize Backend Performance Focus on multithreading and mechanical sympathy principles in .net to deliver low-latency and scalable solutions, ensuring optimal resource utilization across distributed systems.
• Enable configurability and telemetry
  
  
  

Deliver dynamic configuration, management and observability layers for FIX sessions supporting flows with StoneX counterparties

• Collaborate and Troubleshoot: Work closely with cross-functional teams to resolve integration issues, perform system monitoring, and continuously optimize middleware performance through proactive troubleshooting.
• Maintain Documentation and Best Practices : Develop comprehensive documentation, lead code reviews, and adhere to industry standards to sustain software quality and compliance within the evolving technology ecosystem.
• This list of duties and responsibilities is not intended to be all-inclusive and can be expanded to include other duties or responsibilities that management deems necessary.
  
  
  

:

• 5+ Years of Backend Development Experience: Proven track record in backend development, with extensive experience in .net, specifically in building robust, multithreaded, messaging applications and integration services.
• Expertise in Messaging & Middleware Technologies: Demonstrated experience in designing and implementing connectivity layers, ideally using FIX protocols, and integrating messaging systems such as Apache MQ Artemis, Kafka (RedPanda). Ability to design and optimise for REST APIs is a plus.
• (Azure) Cloud Proficiency: Hands-on knowledge of deploying and managing services on Azure, including understanding of cloud-based best practices and DevOps processes.
• Soft Skills & Cross-Functional Collaboration: Strong communication, problem-solving, and teamwork skills, essential for effective collaboration with technical and non-technical teams.
  
  
  

• Experience with High-Performance Systems: Demonstrated success in designing and scaling high-throughput, low-latency systems in a production environment. Open-source project participation.
• Proficiency in Multithreading and Concurrency: Deep understanding of optimizing .net, C++, Java applications for multithreaded execution and resource efficiency.
• Entrepreneurial, DevOps mentality and pragmatism are highly regarded.
• Network engineering and troubleshooting skills
  
  
  

• Advanced Degree in Computer Science or Related Field
  
  
  

Alternatively equivalent years of highly correlated experience

Working environment:

• Hybrid