Top Senior C# Jobs in NYC, NY

Develop cross-platform C++ and Qt software for network device discovery, monitoring, and data collection across Windows and Linux. Build high-performance, concurrent, asynchronous systems that communicate with thousands of devices using SNMP, SSH, ICMP, WMI, and related protocols. Own testing, troubleshoot issues across application, operating-system, and network layers, optimize reliability and performance, and collaborate with backend, UI, QA, and product teams.

Develop scalable C++ software that defines and enforces endpoint behavior across millions of managed Windows endpoints. Responsibilities include implementing features, improving platform performance, shipping production code, designing new systems, writing architecture documents, defining subsystem contracts, and collaborating with server, UI, product, and design teams. The role requires deep Windows systems and kernel-driver expertise, with preferred experience in WHQL, minifilter or WFP drivers, macOS Endpoint Security, and Linux kernel development.

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.

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.

As a Sr. Software Engineer at Bloomerang, you will lead technical direction, mentor engineers, and enhance SaaS solutions while utilizing .NET and AI tools. You will ensure scalable, maintainable applications, advocate for Agile workflows, and focus on quality outcomes in software development.

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.

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.

Lead design, implementation, testing, and support of FreeWheel's high-scale video advertising platform. Own feature lifecycle, produce technical specs, write efficient code, integrate components, and maintain documentation. Provide production support, mentor junior engineers, collaborate with product and operations, and drive technical innovation and architectural decisions.

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

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.

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.

Leads and develops a software engineering team while contributing hands-on to enterprise application design, coding, testing, code reviews, production support, and technical decisions. Builds scalable solutions using C#, ASP.NET, SQL Server, and modern web technologies; partners with product and business stakeholders; supports Agile delivery, CI/CD, troubleshooting, root cause analysis, and engineering best practices. The role also includes mentoring engineers, monitoring delivery and operational metrics, and driving continuous improvement.

Lead a development team while remaining hands-on in full-stack engineering. Design, build, test, deploy, and support secure web applications using C#/.NET, Angular, databases, and AWS. Drive cloud migrations, architecture, CI/CD automation, application security, troubleshooting, performance and cost optimization. Mentor developers, establish engineering standards, lead technical delivery, and collaborate with product, data, DevOps, and architecture teams.

Design, own, and optimize low-latency trading infrastructure supporting real-time data processing, order execution, market data, and strategy implementation. Build fault-tolerant systems, execution logic, venue gateways, test harnesses, and data-analysis pipelines. Partner with quantitative researchers and traders while making architectural decisions, applying modern C++ practices, and supporting systems from design through production. The role requires onsite collaboration four days per week.

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.

Design, build, and operate scalable .NET/C# applications and integrations for Private Wealth. Own end-to-end delivery, write well-tested code, optimize data and queries, troubleshoot production issues, mentor junior developers, and drive platform modernization and CI/CD improvements.

Design and develop low-latency, high-throughput distributed database kernels for massively parallel analytics. Responsibilities include query execution, columnar storage, transaction management, cluster coordination, hardware-aware optimization, SIMD vectorization, RDMA networking, in-database machine learning, vector indexing, performance tuning, architecture reviews, code reviews, mentoring, and resolving scalability issues.

Design and optimize high-performance C++/CUDA libraries for GPU-based data processing. Improve multi-node GPU communication (UcxExchange), optimize Presto GPU query performance, and lead enhancements across Presto, Velox, and cuDF projects for efficient DataFrame and database acceleration.

Develop and maintain the Java client library and high-performance C/C++ server applications. Implement message parsers and feed handlers, optimize for extreme throughput and low latency, build tools for petabyte-scale processing, collaborate on build/deploy/CI practices, monitor uptime, and support smooth feature rollouts.

Implement and maintain the C# client library and high-performance C++ server applications. Build message parsers and feed handlers, optimize for millions of messages/second and nanosecond latency, develop petabyte-scale data tools, collaborate on build/deploy/CI/CD, monitoring, and ensure reliable feature rollouts.

C# developer for fixed income/commodities front-office technology. Full SDLC with support responsibilities; build and maintain trading systems, databases, and UIs using .NET, DevExpress, messaging middleware, SQL Server/Sybase. Requires strong debugging/triage and communication skills. Unit testing and meta-programming, OpenLink/ETRM, and trading product knowledge are desired.

Develop user interface components for ArcGIS Pro using C# and WPF, work in an agile team, and design software solutions for raster and imagery processing.

You will develop and maintain components of the LLVM based toolchain, collaborating with the community while ensuring platform-specific optimizations and tests.