Top C# Jobs in Denver & Boulder, CO

Designs, develops, tests, debugs, and integrates compiler and systems software enhancements. Leads software engineering projects, collaborates with internal and outsourced development teams, resolves complex technical issues, and provides guidance to less-experienced engineers. The role requires hybrid work averaging two days per week in an HPE office.

Develop and maintain commercial scientific visualization software in modern C++ on Windows. Build desktop features across backend engines and user interfaces, improve performance for large datasets, and expand automation, scripting, APIs, and system extensibility. Collaborate with product managers and engineers on architecture, feasibility, code reviews, technical debt, and cross-codebase initiatives while improving customer workflows and software quality.

Develops and maintains .NET applications using C#, Microsoft SQL Server, unit and integration testing. Responsibilities include building features, fixing bugs, debugging across the application stack, making maintainability and performance decisions, researching solutions, communicating design choices, and collaborating with engineering peers. The role requires approximately 2–3 years of C# and MSSQL experience, Agile development experience, and a bachelor's degree or equivalent practical experience.

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.

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.

Develop and maintain PLM and digital engineering applications using C# and .NET. Lead software design, requirements gathering, SDLC planning, coding, testing, code reviews, and technical problem-solving. Collaborate with engineers, business analysts, architects, administrators, and business representatives to deliver application solutions. Improve development quality through automated testing, peer reviews, and development standards while mentoring and guiding team members.

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.

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 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.

Lead modernization of a 30-year-old Store Management System by reverse engineering EZC file-based platforms, migrating data and applications to PostgreSQL, and developing enterprise C/C++ software. Responsibilities include architecture, systems integration, APIs, ETL, performance optimization, troubleshooting, documentation, and maintaining business continuity. The role also applies AI-assisted development tools for code analysis, documentation, testing, and modernization while mentoring teams and supporting legacy and modern environments.

Design and develop massively parallel distributed database kernels for real-time analytics at terabyte and petabyte scale. Responsibilities include low-level C++ development, MPP query execution, SIMD and hardware optimization, distributed communication using MPI and RDMA technologies, database internals, vector indexing, in-database machine learning, performance tuning, architecture reviews, mentoring, and resolving scalability issues.

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.

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, 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.

The C# Engineer will perform full life cycle development in an Agile environment, focusing on C# with potential work in Java, C++, and JavaScript on various projects.