Hired Niels to build my sports court booking SaaS from scratch — Flutter mobile apps (Android/iOS) and Go backend. He handled EVERY engineering aspect solo: beautiful cross-platform apps with real-time features, payments, and a fast, scalable Go API + admin panel. Niels excelled at efficiency — automated CI/CD, smart caching, and cost-optimized architecture that saved me significant money long-term. Communication was proactive, clear.