Top Senior C# Jobs

Develop and maintain core components of a modern digital auction platform using C# and .NET Core. Responsibilities include designing data models, building RESTful APIs, integrating legacy and third-party systems, developing Azure DevOps CI/CD pipelines, troubleshooting performance issues, conducting code reviews, documenting best practices, and collaborating with product managers and multiple engineering teams.

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.

Develop and support the Geneva portfolio management platform and related systems for an asset management business. Responsibilities include building Windows and console applications in C# and .NET, integrating APIs and downstream applications, supporting SQL Server databases, testing deployments, documenting work, resolving production issues, and collaborating with business users on requirements. Financial services, Geneva, trade flow, and hedge fund experience are valuable.

Build and lead large-scale distributed, API-driven systems using C# and .NET. Develop AI-powered agents, intelligent workflows, automation, and observability capabilities across CoStar’s data platform. Design robust software, data models, and integrations with SQL Server and cloud services. Collaborate with Product, Research, and Data teams, establish engineering standards, conduct code reviews, and apply telemetry to improve reliability and operational efficiency.

Develop enterprise and customer-facing media playback solutions within a collaborative development team. Build web and mobile applications using C#, ASP.NET MVC, AngularJS, .NET, JavaScript, Java, Objective-C, Swift, and Python. Implement advanced video security features including forensic watermarking, DRM, and encryption. Collaborate with team members, document technical specifications, communicate with customers, and support project completion.

Design and develop scalable C++ software for endpoint state and control across Windows, macOS, and potentially Linux. Build reliable, multi-process systems that enforce endpoint behavior, manage local state, support IPC, and operate across millions of devices. Responsibilities include implementing features, improving platform performance, writing design documents, defining architecture and IPC contracts, and making technical decisions in an evolving, sparsely documented environment.

Build and scale low-latency ad-serving software handling billions of daily auctions. Responsibilities include developing data- and model-driven features, optimizing algorithms and architectures, reducing cloud costs, extending observability, supporting distributed infrastructure, participating in on-call rotations, and documenting systems and incident procedures.

Designs, develops, tests, deploys, and supports large-scale software for a video advertising platform. Owns feature lifecycles, writes technical specifications and efficient code, integrates software components, documents functionality, and develops quality assurance procedures. Collaborates with product, operations, and engineering teams, provides technical leadership, resolves production issues, researches relevant technologies, and mentors junior engineers. The role requires expertise in C/C++ or Golang, database design, network programming, distributed systems, and large-scale software development.

Develop and support scalable enterprise full-stack applications using C#/.NET and AngularJS. Collaborate with business and technical stakeholders, design and review solutions, build APIs and applications, maintain technical documentation, mentor junior teams, and apply modern architectural patterns including microservices, secure APIs, and cloud technologies.

Design, develop, and maintain cloud-based software using .NET and C#. Collaborate with international teams throughout the software development lifecycle, including architecture, coding, testing, deployment, feature development, and bug fixes. Apply clean-code principles and pragmatic design practices. Support containerized deployments with Docker and Kubernetes, and coordinate effectively across multisite development teams.

Build software, data pipelines, dashboards, and automation for cloud cost visibility, infrastructure efficiency, reliability, engineering productivity, and financial accountability. Analyze workloads and billing data, implement AI- and analytics-enabled forecasting and anomaly detection, develop cloud-native services, and support capacity planning, cost allocation, and optimization. Collaborate with Engineering, Finance, Data, Platform, SRE, Architecture, and Product teams while testing, troubleshooting, documenting, and communicating recommendations and business value.

Develop and maintain sports trading and tools applications and platforms using .NET, C#, and SQL Server. Build scalable, low-latency, highly available software handling high-volume real-time data. Support existing 24/7 trading systems, perform root-cause analysis, collaborate with product owners and testing teams, contribute to solution proposals and estimates, and mentor technical team members. The role will also expand into Golang, React, and Google Cloud Platform.

Develop and maintain scalable enterprise systems, including loan origination, servicing, and customer-facing applications. Design APIs, middleware, integrations, and secure backend services; participate in code reviews, architecture discussions, automation, CI, legacy modernization, troubleshooting, and performance tuning. Collaborate across teams in an Agile and DevOps environment while mentoring peers and promoting modern development practices.

Build and maintain cross-platform endpoint agent capabilities for Windows, macOS, and Linux using Rust and native operating system APIs. Develop secure, concurrent, networked systems integrating with backend services, and own features from design through production support. Investigate complex endpoint issues, improve performance, reliability, security, and upgrades, and contribute through design reviews, code reviews, automated testing, and technical guidance.

Design and build data-driven advertising software features, scale distributed applications and infrastructure, optimize algorithms and architectures, reduce cloud costs, and improve observability. Participate in on-call rotations and incident escalation, create technical documentation and playbooks, and collaborate with distributed teams across time zones. The role requires strong software architecture, performance optimization, data modeling, Linux, and compiled-language expertise.

Design, develop, and optimize high-performance C++ systems software for Linux-based manufacturing intelligence platforms. Build multithreaded and asynchronous architectures, profile performance, debug software-hardware issues, maintain Python tooling, and collaborate with firmware, hardware, and application teams throughout the product lifecycle.

Design and implement high-performance datapath features for load balancing, firewall rules, and Layer 7 protocols. Build scalable networking and security systems using C or C++, data structures, algorithms, and Unix/Linux optimization. Own architectural projects from conception through large-scale deployment while applying advanced knowledge of DNS, HTTP, TCP/IP, and SSL/TLS. Use AI tools to improve engineering workflows and problem-solving.

Develop and test C++ software for FactoryTalk Optix HMI and control-system applications across Windows and Linux. Responsibilities include subsystem design, requirements documentation, implementation, unit and automated testing, debugging, code and design reviews, anomaly analysis, and product quality validation. The role collaborates with global Agile teams, improves development and test automation practices, researches technologies, communicates design concepts, and mentors other engineers.

Design, develop, test, and maintain C#/.NET software products and platforms. Create database stored procedures, SQL scripts, and ETL jobs; optimize relational database performance; and contribute to Agile/Scrum processes. Collaborate across teams, mentor developers, facilitate technical discussions, evaluate emerging technologies, and deliver reliable products that meet specifications and performance SLAs.

Develop and integrate C/C++ ground support equipment software, simulators, test tools, and core applications in a Linux-based classified environment. Responsibilities include requirements and design documentation, testing, peer reviews, configuration management, hardware/software interface support, system integration, deployment, and troubleshooting. Higher-level duties may include technical leadership, mentoring, schedule support, and customer or program discussions. The role is fully onsite in Chandler, Arizona, requires an active Secret clearance, and follows a 9/80 schedule.

Develop and support full-stack web applications for Source-to-Pay business processes. Responsibilities include designing .NET solutions, developing front-end and back-end functionality, integrating RESTful services and databases, troubleshooting production issues, testing, documenting, supporting users, participating in architecture and code reviews, and mentoring junior developers. The role requires collaboration with business stakeholders and ownership of development projects.

Designs and builds scalable, resilient distributed systems and applications using .NET, C#, microservices, REST APIs, cloud platforms, containers, and DevOps practices. Responsibilities include architecture, coding, code reviews, reusable components, monitoring, continuous delivery, infrastructure as code, cross-functional collaboration, mentoring engineers, and improving engineering processes.

Lead maintenance and expansion of a flagship Windows client-server accounting product. Design, implement, test, and document features; maintain large legacy C++ codebase while developing in C#/.NET. Collaborate with cross-functional teams, gather user requirements, optimize databases, ensure code quality, and apply finance domain knowledge to deliver reliable accounting software.

Develop high-performance C++ services and libraries on Linux for real-time systems integrating AI, hardware interfaces, and sensor data. Optimize CPU, memory, I/O, concurrency, and build performance; debug multithreaded issues; write tests; apply sanitizers and static analysis; and contribute to CI pipelines and developer tooling.

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.