Top C# Jobs in Denver & Boulder, CO

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.

Develop and test systems-level C++ software that defines and enforces endpoint behavior. Initially, the engineer will own testing infrastructure and coverage for two active projects, then contribute to feature development. The role requires strong C++ fundamentals, automated testing experience, and interest in operating-system concepts such as processes, file systems, services, and APIs. Work includes learning unfamiliar systems, collaborating effectively, and supporting reliable endpoint security and management capabilities.

Develop and architect a cross-platform C++ endpoint patching agent for Windows, macOS, and Linux. Responsibilities include code reviews, mentoring engineers, improving development processes, collaborating across patching teams, and translating product needs into resilient technical designs. The role involves system-level APIs, patch installation and rollback logic, embedded databases, and client-server integration.

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.

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.

Design, develop, test, document, deploy, and support scalable full-stack applications using React, C#/.NET, and Hack. Build backend services, APIs, integrations, and AI-enabled capabilities including LLM workflows. Participate in Agile planning, code reviews, troubleshooting, client communication, and software delivery while applying modern architecture, DevOps, CI/CD, and automated testing practices.

Build and validate reinforcement-learning tasks for AI agents exploring unfamiliar C repositories. Responsibilities include investigating runtime behavior, rewriting engineering questions, refining rubrics and foils, running validation workflows, documenting solutions, and addressing expert review. Work focuses on production systems such as PostgreSQL, Redis, OpenSSH, OpenSSL, and other foundational C codebases.

Leads hands-on full-stack development across architecture, implementation, testing, deployment, and support. Designs secure, scalable C#/.NET and Angular applications, cloud integrations, APIs, and data solutions on AWS. Guides developers, establishes engineering standards, manages CI/CD and automated testing, troubleshoots complex issues, and drives cloud optimization, security, and technical debt reduction. Collaborates with product, architecture, DevOps, analytics, and project teams while supporting migration of on-premises applications to AWS.

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.

Develop and maintain C++ software for OPIR sensor data processing supporting missile warning, missile defense, battlespace awareness, and technical intelligence. Responsibilities include software design, feature development, prototyping, integration, testing, agile collaboration, and small-project ownership. The role requires Linux, Makefiles, shell scripting, data structures, and eligibility for a DoD security clearance, with preferred experience in modern C++, optimization, testing, containerization, CI/CD, CMake, DevSecOps, and remotely sensed data.

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.

Architects, develops, and maintains high-performance C++ applications with advanced memory management and multithreaded architectures. Owns critical system components, build systems, CI/CD pipelines, containerization, debugging, profiling, and performance tuning. Leads code reviews, technical planning, and system design while mentoring engineers. Works in Linux environments with Python, shell scripting, SQL, and Git, and collaborates across teams to improve reliability, scalability, and technical growth.

Lead end-to-end development of secure, scalable web applications and data solutions supporting clinical trial operations. Design frontend and backend components using C#/.NET, Angular, AWS, and relational or non-relational databases. Guide architecture, testing, deployment, CI/CD, security, cloud optimization, and regulatory compliance. Mentor developers, oversee technical delivery, troubleshoot complex issues, and lead migration and modernization of on-premises applications to AWS.

Develop and maintain high-quality features for insurance software, perform unit and integration testing, debug across OS/DB/app/network layers, fix production issues, and collaborate with peers. Own technical growth, follow industry/open-source trends, and contribute to UI design and Agile development processes.

Develop and maintain backend services and RESTful APIs using C# and .NET. Design and optimize MySQL schemas and queries, troubleshoot production and staging issues, improve performance and scalability, document architecture, and uphold code quality and security. Collaborate with cross-functional teams in a fully remote environment while contributing to development best practices and continuous improvement.

Evaluate AI coding-agent interactions for usefulness, correctness, engineering judgment, reasoning quality, and developer trust. Provide clear, opinionated feedback, distinguish response-quality levels, and help define standards for excellent interactions with tools such as OpenAI Codex, Claude Code, and Cursor. This contract role requires staff- or principal-level software engineering experience and familiarity with modern AI-assisted development workflows.

The C# / .NET Developer will design and maintain middleware applications, build Shopify integrations, and support a mobile app backend in a remote work environment.

Design and evaluate performance engineering tasks for AI training/evaluation. Optimize runtime, compilers, memory, CPU/GPU and concurrency. Produce documented solutions, evaluate AI-generated code, and build evaluation frameworks and scoring rubrics while collaborating with researchers and SMEs.

Design, develop, implement, and analyze technical products. Conduct engineering evaluations and improve product quality. Requires a bachelor's degree and 6 years of experience.

Lead a development team focused on data processing and statistical analysis, ensuring high-quality software development and complex report packaging for clients.

The C# Developer, Analyst will implement and customize software, troubleshoot issues, and engage with clients, balancing coding and business interactions.

Seeking a C# / MVC Developer to convert a VB.NET site to C# / MVC. Responsibilities include full stack .NET development, SQL development, and testing.

The Sr. C# Developer will work in an Agile/Scrum environment focusing on .NET development, rich UI web applications, and commercial software.

Seeking a C# Engineer, Architect to join a team, focusing on development and providing a technology roadmap. Requires strong architecture skills.