Senior .Net Developer
First seen by Alion on Sep 24, 2026.
Role : Senior .Net Developer
About the role :
FitnessForce runs the daily operations of gyms and fitness clubs globally, from member check-in to point-of-sale retail. As a senior backend developer on our core team, you'll own the services and APIs that keep this multi-tenant platform fast, secure, and reliable at scale.
We build with AI as part of our everyday workflow. You'll use tools like Cursor to move faster, while staying fully accountable for the quality, security, and design of everything that ships.
What you'll do :
- Design, build, and maintain scalable, secure REST APIs in .NET Core that support our Angular web app and Flutter mobile app.
- Architect data models and optimize query performance in MySQL, keeping data isolated and available across a multi-tenant platform.
- Build and maintain event-driven services with Apache Kafka to keep data in sync across our integrated systems in real time.
- Lead the technical build-out of core features, including cross-club access, retail workflows, and global integrations.
- Use AI coding tools to speed up development, while owning the maintainability, security, and architecture of everything you ship.
- Grow automated test coverage across backend services to keep releases stable and regression-free.
- Review code, unblock the backend team on hard problems, and set the standard for clean, maintainable engineering.
What you'll bring :
- 6 to 8 years of backend engineering experience, ideally in a SaaS product.
- Deep hands-on expertise in C# and .NET Core.
- Experience using AI coding assistants in production work, with the engineering fundamentals to review, refactor, and stand behind AI-generated code.
- Strong relational database skills, including schema design, transactions, and query optimization in MySQL.
- Experience building multi-tenant systems and working with event-streaming platforms like Kafka.
- A track record of building secure, well-versioned APIs and untangling complex business logic.
Nice to have :
- Familiarity with Docker, container registries, and standard CI/CD pipelines.
- Experience in the fitness, club management, or membership software industry.
- Exposure to how backend APIs connect with Flutter and Angular front ends.
Skills
.Net, C#, MySQL, RESTful API, Kafka, AngularJS, .Net Core, Vibe Coding