Senior Software Engineer (C#)

Senior Staff Software Engineer We are hiring a Senior Staff 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. Responsibilities 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 Tech stack you'll work with: 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, Claude Qualifications What we're looking for: 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 What we offer: Work on mission-critical systems used globally Ownership, and room to grow technically and personally A strong, collaborative engineering culture with talented peers Hybrid work flexibility Support for continued technical and professional development Stonex Group