Top Senior C# Jobs in Chicago, IL

Design, build, and scale low-latency ad-serving systems and data/model-driven features. Optimize algorithms and architectures for performance and cloud cost, extend observability, participate in on-call rotations, and produce runbooks and documentation.

Design, customize, and maintain C++ applications in a Linux environment. Lead releases, collaborate with stakeholders and QA, mentor junior engineers, manage documentation, track performance metrics, and participate in design and peer-programming sessions. May work variable schedules including nights and weekends.

Lead development of core client systems and engine-level infrastructure in Unity/C#. Diagnose and fix cross-cutting performance issues, upgrade third-party SDKs, evolve build tooling, produce design docs, scope multi-week infrastructure initiatives, mentor engineers, and drive profiling, optimization, and architecture changes to enable future features.

Design, build, and maintain high-throughput, low-latency C++ systems for symbol resolution. Develop scalable APIs, participate in design/code reviews, monitor and troubleshoot production, champion best practices, and mentor teammates.

Design, develop, and field high-performance Ground Control Station and C2 software using C++/Qt/QML and QGroundControl. Lead architecture and technical direction, mentor engineers, define APIs/ICDs, debug integration/latency issues, support field tests, implement post-mission debrief tools, and ensure interoperability with C2 standards.

Design, implement, and maintain low-latency C++ applications for trading strategy execution, optimizing performance, and collaborating with traders and engineers.

Design, develop, test, and maintain scalable C#/.NET applications and RESTful APIs. Build data-driven platforms, implement CI/CD and DevOps practices, deploy containerized apps (Docker/Kubernetes) on AWS, troubleshoot production issues, and collaborate on architecture, code reviews, and observability improvements.

Contract .NET developer/consultant role requiring 5+ years experience building web applications using C#, .NET, Entity Framework, SQL Server, LINQ, WCF, MVVM/MVC, and JavaScript frameworks (JSRender, Angular, Node, jQuery, HTML5). 6+ month contract; rate DOE.

The Senior C# Developer will lead AI enablement by transforming APIs into an Agent Mesh using C# and the MCP, ensuring secure AI interactions through Gravitee management.

Design, build, test, and support web and client-server applications; lead custom SharePoint intranet development; implement front-end features using C#/.NET and JavaScript frameworks; optimize performance and scalability; produce technical specifications, documentation, QA, and user training; maintain .NET certifications.

Lead design and global rollout of a high-performance core market data and execution platform. Implement and optimize low-latency market data ingestion, normalization, distribution, and execution components in modern C++. Own deployment, monitoring, profiling, and production optimization while collaborating closely with quants and technical traders to enable systematic pricing and trading strategies.

Lead development of high-performance C++ trading systems and core platform components, build and optimize exchange connectivity (market data and order flow), implement trading algorithms, improve stability and observability, troubleshoot production issues, and collaborate closely with quants and traders to iterate on design and deployment.

The role involves using C++ for software development focusing on object-oriented principles, with projects on Linux and Windows operating systems. It requires strong debugging and testing skills, along with adaptability to new technologies.

The C++ Developer will engage in software development focusing heavily on C++ and object-oriented programming, primarily for Linux and Windows systems.

Develop and maintain .NET Core trading systems for Linux with service-oriented architecture and multi-threaded processing. Implement async, lock-free structures and distributed systems, write unit and integration tests, optimize SQL queries, design data structures and algorithms, and work with communication protocols (SignalR, gRPC, HTTP). Use PostgreSQL, Docker, and AWS in the deployment stack.

Build and optimize high-performance C/C++ and Rust server applications and feed handlers for market data. Implement parsers, petabyte-scale processing tools, and low-latency, high-throughput optimizations. Collaborate on build/deploy/CI, monitoring, and ensure reliable feature rollouts.

Develop and optimize ultra-low-latency, high-performance trading infrastructure in modern C++. Implement and tune order execution, market data connectivity, multi-threaded systems, and risk modules. Profile and benchmark real-time systems, collaborate with quants and traders, and maintain robust, fault-tolerant continuous trading operations.

The role involves developing applications using .Net and SharePoint technologies, requiring a strong background in web application development and multiple programming languages.

Develop high-performance, low-latency trading systems for options market making, collaborating with traders and quants to enhance performance and trading infrastructure.

As a Senior Engineer on the Market Data team, you will design high-performance libraries for trading systems, ensuring fast and reliable market data delivery while collaborating with various teams.

Lead design and delivery of complex backend features for a high-scale online banking platform. Own code from design to production, modernize legacy systems, develop microservices, design APIs, implement tests, ensure secure coding, use AI-assisted tools, troubleshoot issues, and document APIs while collaborating with product, QA, and front-end teams.

As a C++ Software Engineer, you'll develop market data infrastructure, enhance trading systems' performance, and collaborate with researchers to improve trading strategies.

The position involves building and optimizing automated trading infrastructure, developing trading algorithms, and creating scalable applications in a team environment.

Design high-performance C++ libraries for automated PCB design challenges, mentoring peers and shaping technical direction while collaborating with experts in various fields.

Build and maintain scalable, cloud-native APIs using .NET. Enhance core platform components, lead architecture and testing discussions, optimize telemetry and performance, collaborate cross-functionally, conduct code reviews, and mentor team members.