C# .NET Software Engineer

Overview Connecting clients to markets – and talent to opportunity. With 5,400+ employees and over 80,000 institutional, commercial, and payments clients, we operate from more than 80 offices spread across six continents. As a Fortune 100, Nasdaq-listed provider, we connect clients to the global markets – focusing on innovation, human connection, and providing world-class products and services to all types of investors. Whether you want to forge a career connecting our retail clients to potential trading opportunities, or ingrain yourself in the world of institutional investing, StoneX Group is made up of four business segments that offer endless potential for progression and growth. Corporate: Engage in a deep variety of business-critical activities that keep our company running efficiently. From strategic marketing and financial management to human resources and operational oversight, you’ll have the opportunity to optimize processes and implement game-changing policies. Responsibilities Position Purpose We are hiring a Software Engineer to join the API & Middleware Group, a central platform team responsible for building scalable APIs, middleware services, and event-driven systems used across the organization. This role focuses on designing and operating high-performance, low-latency services that run under significant load and strict reliability requirements. You will work on distributed, data-intensive systems that enable system-to-system integration and platform-level capabilities. This role is ideal for an experienced .NET engineer who thrives on ownership, stays up to date with the newest .NET technologies, and brings deep expertise to high-load, low-latency systems. You will collaborate closely with experienced engineers, tech leads, and QA partners, contributing to architecture, implementation, and operational excellence. Technical Ecosystem Languages & Frameworks: C#, .NET Core, ASP.NET Core Architecture: Microservices, event-driven systems (Kafka, Redpanda), CQRS Cloud & Infrastructure: Azure, Kubernetes, Docker, Rancher, TeamCity, Octopus, Grafana Databases: MS SQL Server (T-SQL), NoSQL, PostgreSQL Tooling: GitHub, Visual Studio, VS Code, Rider, ReSharper AI & Developer Tools: MS Copilot, GitHub Copilot, ChatGPT, Claude Primary Duties Will Include Design and develop low-latency solutions using the latest .NET technologies; build performant, scalable backend services from scratch or improve existing ones Write well-designed, testable, and efficient code; ensure designs are in compliance with specifications Tackle live production challenges, including troubleshooting and performance issues Do proof of concepts to test out various ideas and technologies Support continuous improvement by investigating alternatives and technologies and presenting these for architectural review Mentor and support engineers with technical direction and best practices Participate in code reviews (PRs), design sessions, and agile ceremonies; contribute as a strong team player Work closely with team leads, stakeholders, and other teams across the company Continuously explore and evaluate new technologies that could enhance the platform Qualifications To Land this role you will need Minimum 5+ years’ experience building global enterprise-level systems Knowledge of financial markets or a strong desire to learn Proven hands-on experience designing and developing enterprise applications using C# / .NET Core / .NET 8 or higher Solid grasp of .NET Core APIs, high-load systems, multithreading, and performance tuning Experience developing distributed systems using microservice architecture (event-based) Experience with messaging systems like Redpanda and Kafka Hands-on experience with Kubernetes and containerization (Docker); experience working on cloud platforms (Azure preferred) Excellent knowledge of relational databases (SQL) and NoSQL databases Strong communication skills and the ability to collaborate across teams A growth mindset and eagerness to stay current with industry trends Education BS/MS degree in Computer Science, Engineering, or a related subject Working Environment 4 days in office per week