Senior Software Engineer/.NET Developer (On-Site)

Neumo Holdings LLC•Fort Wayne, IN

10d•Onsite

About The Position

We build and maintain the systems that government motor vehicle agencies depend on to test, license and certify drivers. Our software runs in production across more than two dozen jurisdictions in the United States and Canada, where reliability and auditability are contractual obligations rather than aspirations. We are seeking a Senior Software Engineer to design, build and maintain data-intensive enterprise applications across that portfolio. The majority of this work is in C# and .NET, backed by SQL Server. Our front ends vary: some applications are built entirely in Vue.js, one of our primary applications uses Vue selectively, and another uses none at all — so you will move between modern component-based front ends and traditional server-rendered views. Some of our highest-throughput components are written in C++, so working proficiency there — or the appetite to develop it — matters, but .NET is where most of your time will be spent. Success requires strong problem-solving skills, comfort moving across mixed technology stacks, and genuine ownership of delivering reliable solutions in real production environments. You will work in systems that carry years of accumulated business logic, and you will help modernize them without disrupting the jurisdictions that rely on them daily.

Requirements

Strong professional experience with C# and .NET, building and maintaining production web applications and services
Strong experience with SQL Server, including query design and optimization, performance tuning and efficient data access patterns
Strong object-oriented design skills, with a working commitment to SOLID principles and the judgment to apply them pragmatically in existing code
Experience with systems where performance and reliability are critical to business operations
Working proficiency in C++, sufficient to read, debug and modify existing production code, with the willingness to deepen it. We do not expect a C++ specialist, but you will encounter it.
Experience with modern front-end frameworks such as Vue.js, or the ability to pick one up quickly, alongside comfort working in traditional server-rendered front ends
5–8 years of professional software development experience
Experience conducting code reviews and mentoring other engineers
Experience in complex, multi-system or legacy-integrated environments
Ability to debug complex issues across multiple layers — database, backend and UI
Proven ability to design and implement maintainable, scalable systems
Strong collaboration across engineering, QA and product teams
Ability to take ownership of deliverables and drive work to completion
Ability to understand existing systems quickly and make safe, incremental improvements in production
We are looking for an object-oriented developer in the fullest sense: someone who designs with SOLID principles in mind and writes code that others can safely change.
Demonstrated understanding of reliability, scalability, security and maintainability, and the judgment to know which matters most in a given change.
Working knowledge of OWASP secure coding practices

Nice To Haves

Experience with modern AI-assisted development tools such as Claude Code, Cursor or GitHub Copilot
Experience modernizing legacy systems or working in hybrid environments
Experience with mobile development frameworks such as React Native
Experience with UWP
Experience in regulated or compliance-driven environments, for example PCI
Experience working with government or public-sector customers
Experience with CI/CD pipelines, including building and maintaining automated build and release workflows
Azure cloud development experience, including cloud architecture and deploying and operating services in Azure
Deeper C++ experience in production systems

Responsibilities

Design, build and support web applications and services using C# and .NET MVC
Design and optimize SQL Server queries and data access patterns for high-performance transactional systems, with emphasis on query efficiency, indexing strategy and minimizing latency
Contribute to front-end development across a mixed estate — Vue.js applications, partial Vue adoption, and traditional server-rendered views
Maintain and extend core application logic in C++ where our highest-throughput components require it
Troubleshoot and resolve complex production issues spanning database, backend and UI layers
Work within and improve complex legacy systems while maintaining production stability
Contribute to ongoing modernization efforts across legacy and current platforms
Deliver jurisdiction-specific change requests and configuration work to committed dates
Collaborate with QA, Product and cross-functional teams to deliver high-quality releases
Participate in code reviews and help raise development standards
Support automated testing and CI/CD pipeline improvements
Mentor engineers and contribute to the technical growth of the team