Senior Backend .NET Developer

Billee.AI•Dallas, TX

1d•$120,000 - $140,000

About The Position

Billee's billing platform processes utility charges for thousands of multifamily properties across the country. 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.

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

Nice To Haves

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.

Responsibilities

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.
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.
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.
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.
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.