Top C# Jobs in Denver & Boulder, CO

The Senior Software Engineer develops and maintains Sports Trading applications using .NET and SQL Server, enhancing existing functions and providing technical guidance.

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.

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.

Remote backend C# developer to build and optimize a high-load spot-exchange matching engine. Improve performance and API throughput, implement business features, write unit and integration tests, work with .NET Core and PostgreSQL on AWS, and apply multithreading, async, and distributed systems concepts.

Design, implement, and optimize scalable backend software solutions. Collaborate with team members and uphold coding standards while troubleshooting and maintaining software performance.

The Senior Software Engineer will develop and maintain client-side applications, improve installation workflows, and ensure enterprise deployment support for cybersecurity products.

Design, build, and maintain backend workflow orchestration and state management for analyzer integrations on the ECL platform. Modernize legacy .NET systems, ensure reliable event-driven operations, collaborate with integration, infrastructure, and QA teams, and preserve workflow behavior during knowledge transfer.

Lead technical direction for a major product domain, reduce architectural debt, mentor engineers, standardize AI-agent workflows, and design scalable backend solutions integrating LLMs and cloud services. Drive cross-team RFCs, cookbook standards, and adopt agentic AI tooling while balancing security, quality, and delivery.

Develop, optimize, and maintain high-throughput C++ software for processing OPIR and remote sensing data on Linux. Lead small teams, implement algorithms for detection and tracking, improve performance and scalability, support integration/testing, participate in code reviews, mentor teammates, and work directly with customers through the software development cycle in an Agile environment.

Develop and optimize high-throughput C++ algorithms for remote sensor data exploitation (image analysis, detection, tracking). Prototype, integrate, and test software within government frameworks as part of an Agile team. Work full-time in-person in Boulder, CO and obtain/maintain DoD security clearance.

Develop, optimize, and integrate high-throughput C++ algorithms and multi-object tracking software for counter-UAS and remote sensing systems. Work in an Agile small-team environment to prototype, test, and deliver low-latency processing solutions within government frameworks.

The Senior C# Developer will lead AI enablement by transforming APIs into an Agent Mesh using C# and the MCP, ensuring secure AI interactions through Gravitee management.

Lead development of software for an automated parking platform, focusing on multi-agent motion planning, fleet coordination, real-time embedded systems, simulation, integration, and deployment. Build scalable, fault-tolerant C++/ROS2 software, validate via large-scale simulation and live pilots, and collaborate across disciplines to deliver reliable production robotic systems.

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.

Design, build, and maintain backend workflow orchestration and analyzer integrations for the ECL platform. Manage analyzer state transitions, runtime event handling, and legacy modernization; extract shared .NET libraries, collaborate with integration and QA, and support knowledge transfer.

Develop and maintain .NET-based web applications and services (REST/SOAP). Work on full-stack features using ASP.NET, WebAPI, client-side frameworks (Angular, jQuery, MVC), and SQL Server. Diagnose and optimize performance, threading, and memory usage. Implement secure, scalable, multi-threaded distributed systems, write unit/integration tests, and translate business requirements into technical designs.

Design, develop, and maintain C#/.NET web applications and services (REST/SOAP). Implement client-side features using MVC/JavaScript frameworks, optimize performance and memory/threading, perform SQL Server tuning, and write unit/integration tests. Translate business requirements into scalable, secure distributed solutions.

Design, develop, and maintain .NET/C# web applications and services (REST/SOAP). Build scalable, multi-threaded distributed systems; profile and optimize memory, threading, and performance; implement client-side features (MVC, JavaScript, Angular, Bootstrap); perform T-SQL and SQL Server performance tuning; create unit and integration tests; translate business requirements into technical designs.

Design, develop, and optimize .NET web applications and services using C#, ASP.NET, WCF/WF, Web API and REST/SOAP. Implement client-side features (Angular, jQuery, MVC), ensure security, perform DB tuning on SQL Server, write unit/integration tests, and resolve threading/memory/performance issues for scalable distributed systems.

Develop and maintain .NET Core trading systems for Linux with service-oriented architecture and multi-threaded processing. Implement async, lock-free structures and distributed systems, write unit and integration tests, optimize SQL queries, design data structures and algorithms, and work with communication protocols (SignalR, gRPC, HTTP). Use PostgreSQL, Docker, and AWS in the deployment stack.

Contribute to and optimize the performance of ClickHouse, assist with debugging, collaborate with teams, and engage with the open-source community.

Develop and optimize ultra-low-latency, high-performance trading infrastructure in modern C++. Implement and tune order execution, market data connectivity, multi-threaded systems, and risk modules. Profile and benchmark real-time systems, collaborate with quants and traders, and maintain robust, fault-tolerant continuous trading operations.

The Back End Software Engineer will design and build scalable services for a SaaS platform, collaborate with teams, and contribute to quality code and architecture discussions.

Design high-performance C++ libraries for automated PCB design challenges, mentoring peers and shaping technical direction while collaborating with experts in various fields.

Develop a quest gameplay engine for game server and mobile apps and build a visual no-code quest editor. Collaborate in one-week Scrum sprints, design software architecture, and use C++/Qt, JavaScript/TypeScript, git, and Linux.