Top C# Jobs

Design, build, and scale high-performance ad-serving systems. Optimize algorithms and architectures to reduce cloud costs, extend observability, support incidents via on-call rotations, and produce documentation and playbooks.

Develop, maintain, and deploy low-latency, cloud-based ad-serving software using C++ and Linux. Work on distributed systems, databases (Snowflake, Aerospike), and network programming; collaborate with QA and stakeholders, review code, optimize algorithms, and document designs. Expect team collaboration, variable schedules, and continuous learning.

Develop and enhance performance-critical C++ applications for ultra-low latency trading systems, collaborating across teams to analyze and optimize performance.

The role involves designing, developing, and testing C++ applications for trading systems, collaborating with traders, and ensuring application reliability.

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

As a Backend Engineer, you'll improve Git and Gitaly by contributing features, bug fixes, and performance improvements, collaborating with the open source community, and participating in architectural discussions.

Responsibilities include developing scalable server-side features, optimizing performance, and collaborating with teams to enhance online services for games.

Develop scalable server-side features, online services, and collaborate with teams. Requires C#, .NET expertise and experience in distributed systems.

The Sr. Software Engineer will design and optimize ad delivery systems, implement solutions on AWS, and provide technical leadership while mentoring junior engineers.

Lead design, develop, test, and operate ultra-low-latency C++ trading connectivity and risk modules on Unix/Linux. Integrate FPGA pipelines with C++ for deterministic performance, automate remediation, establish latency/throughput/resiliency tests, and drive AI-assisted engineering adoption across the team.

Lead technical design and deliver secure, scalable C#/.NET software for trading systems. Drive architecture, coding, code review, automation, resiliency, CI/CD, and adoption of AI-assisted engineering practices while mentoring teams and engaging vendors.

Lead engineering role building and evolving the Sigma data-visualization platform: develop C++/Rust->WASM engine, integrate Apache Arrow, build TypeScript/React (Next.js) front-end, extend data adapters, tune WASM performance, ensure secure high-quality production code, drive architecture decisions, evaluate vendors, and lead engineering communities to improve operational stability.

Lead design and delivery of ultra-low-latency electronic trading systems (Smart Order Router, Matching Engine, Market Access, Risk Management). Develop and enhance trading strategies, ensure scalability and reliability, conduct code reviews and testing, and collaborate with cross-functional teams following Agile practices.

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

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.

Build and scale Buyercloud ad-serving systems that process billions of auctions daily. Design data- and model-driven features, optimize performance and cost, extend observability, participate in on-call rotations, produce documentation and playbooks, and support production incidents.

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.

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.

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.

Maintain and improve Advisor360°'s SaaS platform by diagnosing complex issues, optimizing performance and availability, designing serviceability tooling, and collaborating with Engineering, QA, DevOps, and Infrastructure. Mentor teammates, ensure coding standards, participate in on-call rotations, and support global infrastructure deployment and scalability.

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

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

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.

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.