Senior Backend .NET Developer

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 (WebForms/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. Who We Are 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 Core Responsibilities 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. REST API Development: Build and extend .NET 8 APIs that serve our modern JavaScript frontend. These APIs are a core piece of our modernization strategy and require clean, intentional design alongside the day-to-day maintenance work. 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. Requirements 8+ years of backend development experience in the .NET ecosystem Strong command of C# and ASP.NET Experience with relational databases, including SQL Server, PostgreSQL, 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 Ideal Candidate Comfortable in legacy systems — You don't cringe at .NET 4.8 or WebForms. 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 quickly, communicate clearly, and don't close the ticket until the root cause is understood. Builds with the whole system in mind — You think about how changes ripple through a connected platform. You ask questions before making decisions that could affect integrations or data integrity downstream. Self-directed — You can take an issue from description to resolution without needing step-by-step oversight. You know when to surface a decision and when to just make the call. Collaborative without friction — You contribute to architecture discussions, give useful code review feedback, and communicate progress in a way that keeps the team aligned. Detail-oriented — Billing software demands accuracy. You catch edge cases, validate your work against real data, and build in a way that your teammates can trust. Tech Stack You’ll work across three layers of the platform: ezVantage (current platform): .NET Framework 4.8, ASP.NET WebForms and MVC, AngularJS, PostgreSQL New API Layer: .NET 8, REST APIs (Backend-for-Frontend pattern), Azure App Service Modern Portal (in development): TanStack Start (React), server‑side rendering, consuming the .NET 8 backend Prior experience with the current platform stack is not required. Comfort working across both legacy and modern environments is. Where You’ll Sit This role is part of our Engineering team. Your primary collaborators will be the platform and portal teams — you’ll work closely with both on technical decisions, API contracts, and modernization planning. Compensation & Benefits Health, dental, and vision insurance 401(k) Paid time off and flexible work arrangements Professional development opportunities Opportunity for earned equity #J-18808-Ljbffr