Top C# Jobs

Design, develop, and maintain secure, high-quality production code across C#/.NET and Java Spring Boot systems. Produce architecture and design artifacts, apply SDLC and CI/CD practices, use enterprise AI-assisted development tools, and analyze data to improve resiliency and code hygiene. Troubleshoot complex issues and ensure operational stability.

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.

Software Engineers at Citadel develop software solutions for trading platforms, optimizing performance and functionality, and support trading activities.

Designs, develops, tests, and troubleshoots secure, stable .NET applications. Writes high-quality C# code, works across the SDLC, uses CI/CD and AI-assisted dev tools, and collaborates within agile teams to ensure operational stability.

Lead development of a distributed, multi-asset Order Management System (OMS): design and implement core OMS infrastructure (workflow engine, pipeline, caching, event distribution), build automated deployment, improve legacy systems, ensure low-latency, high-availability, and support production stability while mentoring teams and evaluating vendor/architectural solutions.

Design and develop low latency, high-performance trading systems. Optimize code and solutions for hardware efficiency, ensuring seamless application integration.

Design, build, and maintain scalable backend and distributed systems while operating in AI-augmented workflows. Validate AI-generated outputs, contribute to architecture and system evolution, produce technical documentation and prompts, mentor peers, and collaborate with Product, UX, and Engineering teams to ensure reliability, observability, and engineering quality.

Lead development and design for global credit-card authorization systems. Create technical designs, implement complex features in C, write C++ unit tests (Google Test), define interfaces, improve CI/CD and development processes, lead code reviews, mentor junior engineers, and collaborate with product and other technical leads.

Write and maintain efficient C++ code, support design and development of new applications, implement unit and integration tests, document processes, analyze integration needs and system architecture, collaborate with QA, troubleshoot performance issues, and work variable schedules as needed.

As a Software Development Engineer, you will create high-performance Linux software components, ensure system reliability, collaborate with teams, and design security features for containers in cloud environments.

The Market Data Engineer will design and implement high-performance market data systems, focusing on trading infrastructure, performance optimization, and system resiliency.

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.

The role involves building and supporting production-level trading systems in C++ for credit and rates products, collaborating with traders and quantitative researchers.

Design and implement high-performance GPU-accelerated software using C++ and CUDA. Develop CUDA kernels for signal and image processing, profile and optimize GPU applications, integrate with hardware (FPGAs, SoCs), collaborate with cross-functional teams, and apply DevSecOps/CI-CD practices to deliver production-quality defense systems.

Design, develop, and own high-performance C++ cloud-based ad-serving and distributed systems. Mentor junior engineers, collaborate with stakeholders, optimize algorithms, deploy and maintain Linux-based services, use Snowflake and Aerospike, review code, and improve system reliability and scalability.

Software Engineers at Citadel develop, maintain, and support high-performance trading platforms, focusing on custom software solutions and system stability.

The Senior Software Engineer develops and maintains Sports Trading applications using .NET and SQL Server, enhancing existing functions and providing technical guidance.

Develop and maintain custom options valuation and risk-management systems. Collaborate with traders, risk managers, and quants to gather requirements, design solutions, implement high-performance code, troubleshoot issues, document models and tests, and improve scalability, accuracy, and performance of pricing systems.

As a C++ Software Engineer, you will optimize performance for latency-critical systems, collaborate with traders and quants, and ensure code correctness in a fast-paced environment.

Design, implement, and optimize high-performance C++ APIs exposing a mortgage analytics library for interest rate modeling, prepayment/default analysis, derivative valuation, hedging, and forecasting. Collaborate with business, model development, validation, and IT; improve library performance, safety, reliability, and usability; deploy and test production code.

Design, implement, test, and deploy high-performance C++ APIs exposing a mortgage analytics quantitative library for interest rate modeling, prepayment/default analysis, derivative valuation, hedging, and forecasting. Improve performance, reliability, and usability of the library and collaborate with business, model development, validation, and IT teams.

As a Full Stack Engineer, you'll develop online services features using C#, React, and ensure best practices in software development. Collaboration with global teams is key.

Lead architecture and implementation of high-performance C++ and Python systems, integrate distributed and real-time systems, own CI/CD and build tooling, debug multi-threaded systems, guide cross-team integration and mentor engineers, and evaluate new technologies to improve simulation and autonomy platforms.

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.

Lead architecture and implementation of high-performance C++ and Python systems, integrate distributed systems and simulation tools, own CI/CD pipelines, debug real-time multi-threaded systems, mentor engineers, and drive end-to-end integration across simulation and operational platforms.