Backend Developer

About the role

FitnessForce runs the daily operations of gyms and fitness clubs globally, from recurring membership billing to point-of-sale retail. As a senior backend developer on our revenue operations team, you'll own the payment and billing infrastructure that keeps transactions secure, accurate, and reliable across dozens of markets.

You'll work directly with global payment gateways, PCI compliance, and financial data at scale, using AI coding tools like Cursor to move fast without compromising security.

What you'll do

• Architect integrations with global payment gateways, including Stripe and Razorpay, to handle recurring subscriptions, retail transactions, and refunds
• Build reliable webhook processing and idempotency safeguards that prevent duplicate charges and keep transactions consistent
• Design and maintain REST APIs in .NET Core that support our Angular and Flutter apps
• Enforce PCI-DSS compliance through server-side tokenization and secure credential vaulting, so raw card data never touches our servers
• Build event-driven services with Apache Kafka to keep financial ledgers and billing states in sync in real time
• Architect data models and optimize MySQL performance across a multi-tenant platform
• Use AI coding tools to accelerate delivery of complex financial systems, while owning the security and maintainability of everything you ship

What you'll bring

• 6 to 8 years of backend engineering experience in a SaaS product
• Deep hands-on expertise in C# and .NET Core
• A strong track record integrating payment gateway APIs, including subscription lifecycles, webhooks, and multi-currency transactions
• Experience using AI coding assistants in production, with the fundamentals to debug and support AI-generated code in sensitive financial workflows
• Strong relational database skills, including transaction management and query optimization in MySQL
• Experience building multi-tenant systems and working with event-streaming platforms like Kafka

Nice to have

• Familiarity with Docker, container registries, and CI/CD pipelines
• Experience in the fitness, club management, or membership software industry
• Understanding of how backend APIs connect with Flutter and Angular front ends