Senior Backend .NET Developer

Billee.AI•Dallas, TX

7h•$140,000 - $170,000

About The Position

Senior Backend .NET Developer Overview Billee Technologies is looking for an experienced Senior Backend .NET Developer to maintain and enhance our production billing platform. You'll join as a key technical contributor, focusing on bug fixes, feature enhancements, and system reliability while supporting our modernization initiatives and growing customer base. You'll work in a mixed codebase—our legacy .NET 4.8 platform (WebForms/MVC) alongside a new .NET 8 API layer. Your primary focus will be on bug fixes, feature improvements, and system stability, with opportunities to contribute to both maintenance and new API development. You'll be part of a collaborative 10-person engineering team with a clear technical roadmap, making real impact on utility billing for thousands of multifamily properties. We value willingness to work in legacy codebases and provide team support for learning the older stack. 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.

Requirements

8-12 years of backend development experience with .NET ecosystem
Strong expertise in C# and ASP.NET
Experience with relational databases (SQL Server, PostgreSQL, MySQL, etc.)
Experience maintaining and enhancing production applications
Strong debugging and troubleshooting skills in production environments
Experience with multi-tenant SaaS platforms
Excellent analytical and problem-solving abilities
Strong team collaboration and communication skills

Nice To Haves

Experience with .NET 8 or modern .NET Core
Experience with or willingness to learn .NET Framework 4.x and ASP.NET WebForms/MVC
PostgreSQL experience
Azure App Service and Azure infrastructure experience
Property management or billing domain knowledge
Experience with IIS and Windows-based deployments
Background in AngularJS
REST API design and development

Responsibilities

Maintain and enhance production billing platform serving active customer base
Troubleshoot and resolve bugs across legacy .NET 4.8 application and new .NET 8 API layer
Implement feature improvements and enhancements to existing functionality
Develop new REST APIs in .NET 8 for modern JavaScript frontend
Support integrations with property management systems
Optimize system performance and resolve complex production issues
Collaborate with platform and portal teams on technical decisions
Contribute to modernization efforts led by senior architects
Apply industry best practices while respecting constraints of production systems