Senior Backend .NET Developer

Billee's billing platform processes utility charges for thousands of multifamily properties across the country. When it's running well, property managers don't think about it. When it isn't, it's all they think about. This role exists to keep that platform stable, responsive, and moving forward.

You'll spend most of your time working across two codebases: our legacy .NET 4.8 platform (Web Forms/MVC) and a newer .NET 8 API layer we're actively building out. The day-to-day involves diagnosing production issues, shipping bug fixes, implementing feature enhancements, and developing REST APIs that power our modern frontend. This isn't greenfield work — it's the kind of engineering that keeps a real product serving real customers while the foundation gets stronger underneath it.

This role is a good fit for someone who takes production reliability personally and finds satisfaction in untangling a complex system rather than building in a vacuum. You'll have clear senior architects driving the modernization roadmap, a collaborative 10-person team, and enough autonomy to do the work well.

Billee Technologies Inc. is a Dallas-based SaaS startup revolutionizing utility billing for multifamily apartment communities. Our intuitive, cloud-based platform streamlines operations, eliminates inefficiencies, and increases NOI for property owners and operators.

At Billee, we are more than just a technology company. We are a team of innovators and problem solvers. Led by seasoned product and technology practitioners, we challenge traditional providers by offering smarter, more efficient solutions for this overlooked pocket in multifamily proptech.

Our culture is the foundation of our success. We believe in empowering and developing our people, ensuring they thrive both professionally and personally. Our core values define how we work and what we stand for:

• Win Together — We believe in collaboration and collective success. When one of us wins, we all win
• Lead with Integrity — We hold ourselves accountable, operate with transparency, and always do what we say we'll do
• Relentless Determination — We tackle challenges head-on, with persistence and decisive action
• Bold Voices — We encourage open dialogue and foster a culture where every voice matters
• Stay Curious — We are lifelong learners, always seeking new ways to innovate, improve, and grow

Platform Maintenance and Bug Resolution: Triage and resolve issues across both the legacy .NET 4.8 application and the .NET 8 API layer. Production stability is the baseline — this means owning bugs through to resolution, not just flagging them.

Feature Development: Implement enhancements and new functionality across the platform. This includes scoping changes within existing systems and building net-new capabilities that serve the billing workflows our customers depend on.

Integrations Support: Maintain and improve integrations with property management systems. These connections are critical to data accuracy across the platform and require both technical fluency and an understanding of how the data flows end to end.

Modernization Contribution: Collaborate with senior architects on the longer-term technical roadmap. You'll contribute to migration and modernization work while respecting the constraints of a live production environment serving active customers.

• 8+ years of backend development experience in the .NET ecosystem
• Strong command of C# and ASP.NET
• Experience with relational databases, including SQL Server, Postgre
  
  SQL, or MySQL
• Demonstrated experience maintaining and enhancing production applications at scale
• Strong debugging and troubleshooting skills in production environments
• Experience with multi-tenant SaaS platforms
• Clear written and verbal communication skills, with the ability to collaborate across a distributed engineering team

Comfortable in legacy systems — You don't cringe at .NET 4.8 or Web Forms. You understand that production constraints are real and approach older codebases with curiosity rather than contempt.

Production-minded — You treat system stability as a core responsibility. When something breaks, you move…