Top Senior .NET Developer Jobs in Denver & Boulder, CO

Own and evolve Swyfft’s partner-facing insurance API, including resource design, versioning, backward compatibility, authentication, rate limiting, error handling, metrics, documentation, and contract testing. Build production C# code, maintain the translation layer between public APIs and internal systems, support partner integrations, and collaborate with QA and product. The role requires substantial public API experience, strong API security and multi-tenancy knowledge, and fluency in C#, ASP.NET Core, SQL Server, and Azure.

Designs, develops, maintains, and troubleshoots scalable software applications using .NET, SQL Server, UI frameworks, and cloud technologies. Collaborates with product owners, developers, testers, and technology leads; participates in code reviews; writes documented code; and improves software development practices.

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.

Leads architecture and development of complex backend services for a commercial health plan platform. Designs .NET Core and Azure systems, develops claims, eligibility, and benefits functionality, manages healthcare data integrations, and owns cloud infrastructure and CI/CD architecture. Provides technical leadership through code reviews, testing standards, mentoring, and architecture decisions while ensuring performance, reliability, security, and regulatory compliance.

Develop and optimize Microsoft .NET applications, legacy systems, and microservices with a focus on performance, scalability, reliability, and observability. Responsibilities include code reviews, performance testing, CI/CD integration, architecture and sprint delivery, legacy code and SQL tuning, cloud application deployment on Azure, automated testing, and resolving customer issues. The developer collaborates with architects, QA, technical support, and cross-functional teams using SAFe Agile practices.

Senior .NET Software Engineer responsible for end-to-end software development using Microsoft technologies. Requires extensive experience in SDLC, design principles, technical documentation, web application development with .NET, Agile/SCRUM, Entity Framework, database design, and version control. Familiarity with project tools JIRA, TEMPO, Bitbucket, and Confluence preferred.

Senior .NET Web App Developer responsible for designing and building .NET web applications, implementing Oracle PL/SQL solutions, using Entity Framework and Blazor, applying design principles, producing technical documentation, performing performance tuning, and collaborating in Scrum/Agile teams with Bitbucket, JIRA, Tempo, and Confluence.

Develop and maintain web-based applications using .NET/C#, JavaScript, HTML/CSS, SQL and Oracle/SQL Server. Perform root cause analysis, collaborate with teams for requirements, follow Agile SDLC, present change demonstrations, and use Azure DevOps/Jira for lifecycle management. Implement and maintain Blazor components.

Design, build, and maintain production-grade .NET web applications and APIs on Azure. Own full-stack delivery from data models and SQL to front-end components, CI/CD, testing, and architecture. Collaborate with product and delivery teams, participate in code reviews, and ensure secure, observable, well-tested services.

Leads the design, development, and implementation of full-stack applications using C#, .NET, Angular, Azure, and SQL Server. Collaborates with cross-functional teams, ensures application security, performance, and scalability, applies Git-based version control practices, mentors developers, and stays current with emerging technologies.

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 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 development of secure, scalable digital banking software across front-end and backend systems. Design Angular or React applications, build APIs, optimize SQL performance, integrate third-party platforms, improve code quality, implement testing strategies, and mentor engineers. Collaborate with cross-functional teams in an Agile environment while supporting cloud-native practices, regulatory compliance, and continuous product improvement.

Owns the design, development, testing, deployment, and maintenance of production software. Builds C#/.NET backend services, Angular web applications, and .NET MAUI mobile apps; optimizes SQL Server databases; resolves production issues; improves reliability, security, performance, and observability; writes tests and documentation; participates in code reviews; and translates ambiguous business needs into maintainable technical solutions.

Build scalable backend-heavy services and applications using C# and .NET, while contributing to Angular and TypeScript UI development. Design and develop REST APIs and microservices, work with relational databases, implement automated testing and CI/CD, and ensure system security, scalability, and performance. Preferred work includes event-driven architectures, messaging systems, NoSQL databases, caching, search technologies, and mentoring engineers or leading technical initiatives.

The Senior .NET Software Engineer will drive development of .NET software products, focusing on back-end engineering, code reviews, and collaborating with cross-functional teams.

Senior backend-focused software engineer building modern SaaS ERP products for local governments. Responsibilities include designing REST APIs, domain logic, data models, background workflows, and secure auditable systems using C#/.NET, ASP.NET Core, EF Core, SQL Server, and Azure. The role owns capabilities from discovery through deployment and production support, contributes to testing, CI/CD, observability, architecture, code reviews, mentoring, and modernization of legacy applications.

As a Senior Software Developer, you'll design, build, deploy, and support web applications using the .NET stack and Azure, while collaborating with a team.

Seeking a Senior Software Developer to design, build, deploy, and support web applications using the .NET stack and other technologies in a collaborative team environment.

Lead design and delivery of scalable, reliable software using C#/.NET, SQL Server, React, and Azure. Own complex initiatives from design through operations, mentor engineers, improve CI/CD, observability, and apply DDD/TDD/VSA practices. Use modern APIs, microservices or modular monoliths, and AI-assisted tooling to improve delivery.

Seeking a Senior Full Stack .NET Developer to work on a social good project, with strong skills in C#, AngularJS, design, and UX. Requires 5+ years of experience.

The Staff Engineer will leverage 5+ years of experience in C#, JavaScript, and frameworks to lead and innovate solutions in a collaborative environment.

Provide technical leadership and application development for Microsoft-centric solutions: gather requirements, design architecture, mentor teams, manage projects, develop and test .NET/SQL applications, and implement integrations (SharePoint, BizTalk, Azure, Dynamics CRM, web services). Client-facing role with up to 25% travel.

Senior .NET Developer to build a Compliance System (ORCA). Develop distributed RESTful web/cloud services and Web APIs using ASP.NET/C#, backend databases (MongoDB, SQL Server 2012), and frontend tech (AngularJS, HTML/JavaScript, Bootstrap). Work with AWS and Pivotal products; deliver enterprise-grade solutions.

Full‑stack senior .NET developer responsible for 80% hands‑on development, code reviews, mentoring, and 20% testing, deployment, and design. Deliver clean, well‑documented, high‑performance applications using C#, ASP.NET/MVC, SQL Server and UI libraries, integrate with web services, and guide teammates to robust solutions.