Top C# Jobs in NYC, NY

Develop high-performance C++ systems for systematic investing, including real-time data processing, low-latency trading execution, and machine-learning inference tools. Design scalable distributed systems and resilient data pipelines, maintain critical production platforms, and build greenfield solutions in collaboration with quantitative researchers. Ensure software correctness, reliability, performance, and fail-safe operation in live-market environments while aligning technical work with business value.

Develop and optimize high-performance C++ infrastructure for quantitative trading, including order management, market data, trading systems, and data platforms. Build scalable distributed systems emphasizing execution speed, memory efficiency, reliability, and throughput. Collaborate with engineers and quantitative researchers on new infrastructure and technical solutions. Requires modern C++, systems programming, networking, concurrency, Linux, and production software development experience.

Design, develop, and support high-performance equities OMS and electronic trading systems. Build low-latency C++ solutions, FIX connectivity, market data integrations, exchange interfaces, routing, execution, and risk controls. Collaborate with traders, product, operations, and risk teams; lead architecture and code reviews; optimize reliability and performance; and resolve production issues. The role also involves mentoring developers and advancing AI-assisted engineering practices.

Deploys, integrates, hardens, and operates modular C-UAS data and software platforms in secure DoD environments. Builds data pipelines across classification boundaries and disconnected conditions, integrates mission systems, manages Kubernetes-based infrastructure, supports accreditation, and handles observability, incident response, upgrades, and backup recovery. The role also documents solutions, trains mission teams, represents field needs to engineering, and mentors junior forward-deployed data engineers. Most work is remote with occasional travel to restricted environments and SCIFs.

Design and build high-throughput, low-latency market data infrastructure in modern C++ for global equities, futures, and options venues. Develop reusable libraries for market data decoding, normalization, publishing, and consumption; collaborate with quantitative researchers; troubleshoot production issues; and maintain reliable 24/7 systems. The role requires strong concurrency, lock-free algorithm, memory-model, compiler optimization, serialization, and Python scripting expertise.

Develop, test, maintain, and support enterprise applications and services using C#, .NET, ASP.NET Core, Web API, Entity Framework Core, and SQL Server. Responsibilities include API and database integration, code reviews, automated testing, debugging, performance improvements, release readiness, production troubleshooting, and collaboration with product, architecture, QA, and operations teams.

Build and support complex features across C#/.NET back-end services and React front ends. Responsibilities include technical design, API and data modeling, secure and tested coding, production troubleshooting, code reviews, mentoring, documentation, and improving engineering practices. Collaborate with Product, QA, DevOps, Technical Leads, and architecture teams while balancing delivery, maintainability, performance, accessibility, observability, and security.

Develop and maintain macOS systems software using modern C++, Swift, and Objective-C++. Work with process models, IPC, Endpoint Security, Network Extension, security and cryptography APIs, device and storage frameworks, packaging, deployment, and MDM tooling. Profile and debug performance using Instruments, LLDB, os_log, and os_signpost, while creating tests with XCTest, sanitizers, fuzzing, and xcodebuild CI. Support shared codebases across macOS, Windows, and Linux.

Develop and maintain cross-platform macOS systems software using modern C++, Swift, and Objective-C++. Work with IPC, daemons, system extensions, network and endpoint security, device and storage APIs, code signing, packaging, and deployment. Profile and debug performance issues, build automated tests and CI pipelines, and support Apple Silicon and Intel systems. Nice-to-have experience includes SwiftUI, AppKit, macOS beta testing, and shipping EDR, antivirus, network security, or device-management products.

Design, implement, test, and modernize backend services and integrations (TypeScript/Node.js and C++). Lead large projects, write technical specifications and API contracts, enforce coding standards, coach engineers, and drive legacy-to-modern migrations within online banking and core systems.

Design, build, and optimize ultra-low-latency distributed trading systems in modern C++. Collaborate with quantitative researchers and traders to translate strategies into production systems, develop execution capabilities, and improve latency, scalability, reliability, and performance. Responsibilities include multithreaded systems programming, networking, Linux optimization, electronic trading connectivity, and potentially hardware acceleration using FPGA technology.

Design and develop high-performance C++ platforms, services, and infrastructure supporting ETF technology. Build data processing, messaging, connectivity, workflow, and integration components for real-time and reference data. Improve production-system performance, resilience, scalability, monitoring, and observability while collaborating with engineers, researchers, and business stakeholders. Contribute to architecture, testing, code quality, and long-term platform strategy.

Leads the architecture, development, and delivery of a global equity derivatives pricing platform and RFQ workflow. Develops Java server and C# client features, designs REST-based solutions, maintains automated test suites, improves CI/CD pipelines, and supports deployment strategies. The role includes requirements refinement, architecture planning, proof-of-concepts, agile delivery, compliance, mentoring engineers, and collaboration with business and platform partners.

Develop and maintain low-latency, end-to-end high-frequency trading infrastructure from research and simulation through production execution. Partner with researchers on equity and ETF trading systems, build pricing and trading models, deliver frequent production code changes, and ensure robust architectural and operational standards. The role requires strong C++ expertise, computer science fundamentals, and an understanding of trading and exchange systems.

Develop high-performance C++ software for fixed-income electronic and quantitative trading, including automated quoting, execution, risk management, foundational frameworks, and quant libraries. Collaborate closely with traders and quantitative researchers on complex engineering problems. The role requires trading systems experience, Linux proficiency, and a technical or quantitative degree, with Python, rates pricing, networking, and transactional technology experience preferred.

Develop and maintain C++ components for a low-latency middle-office trading system. Responsibilities include integrating third parties, owning modules, implementing enhancements and bug fixes, optimizing latency, scale, and resiliency, debugging production systems, and supporting deployment and client rollouts. The role requires collaboration with distributed engineering and client-facing teams, knowledge of financial trading data, and proficiency in Linux-based C++ development.

Build and lead high-performance browser features in modern C++ and Chromium, including tracker blocking, subscription integrations, and responsiveness monitoring. Own complex projects from proposal through post-mortem, solve ambiguous technical problems, make architecture decisions, collaborate asynchronously with product and design, and use metrics to evaluate outcomes in a large-scale consumer codebase.

Build and maintain scalable, cloud-native APIs and high-value core system components using .NET and related technologies. Lead software architecture and testing discussions, enhance core offerings, collaborate cross-functionally, and ensure quality through code reviews, unit testing, functional testing, telemetry, and performance tuning. Mentor teammates and contribute to continuous technical and process improvement.

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

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

Design, build, and maintain Stellar Core, the distributed system powering the Stellar blockchain. Responsibilities include developing scalable network components, improving peer-to-peer and processing performance, strengthening resilience and decentralization, investigating bottlenecks, authoring protocol specifications, and contributing to architecture, code reviews, and open-source engineering practices.

Develop and maintain a high-performance C++ quantitative library for options analytics. Responsibilities include API and library design, performance profiling and optimization, implementing numerical pricing models, code reviews, developer support, build and CI improvements, testing, documentation, and AI-assisted development. The role works closely with quants and the CTO in a small hybrid 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.

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.