Senior Backend .NET Developer

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.

Core 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

What You'll Find

• Mixed codebase: legacy .NET 4.8 platform (WebForms/MVC) alongside new .NET 8 API layer
• Willingness to work in legacy codebases valued - team support for learning the older stack
• Opportunity to contribute to both maintenance and new API development
• Primary focus on bug fixes, feature improvements, and system stability
• Collaborative 10-person engineering team with clear technical roadmap
• Real impact on utility billing for thousands of multifamily properties

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

Preferred Qualifications

• 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

Technology Stack Current Platform (ezVantage):

• .NET Framework 4.8
• ASP.NET WebForms and MVC
• AngularJS
• PostgreSQL

New API Layer:

• .NET 8
• REST APIs for modern frontend (Backend-for-Frontend pattern)
• Azure App Service

Modern Portal Stack (in development):

• TanStack Start (React)
• Server-side rendering
• Consuming APIs from .NET 8 backend

Compensation & Benefits

• Salary Range: $140,000 to $170,000
• Health, dental, and vision insurance
• 401(k)
• Paid time off and flexible work arrangements
• Professional development opportunities
• Opportunity for earned equity

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