React + Firebase: Architecture Decisions for a Production ERP

Building an ERP is not a side project. It handles real money, real tax obligations, and real business data. Every architecture decision has consequences that compound over months. Here is what I chose for Frihet, and the reasoning behind each decision. The stack Frontend: React 18 + TypeScript + Vite 5 Styling: Tailwind CSS + shadcn/ui + Radix Backend: Firebase (Auth, Firestore, Cloud Functions, Storage) AI: Google Gemini (2.5 Flash + Pro) Payments: Stripe Billing + Connect Hosting: Vercel (frontend) + GCP europe-west1 (backend) Mobile: Capacitor (iOS + Android from same codebase) Why Firebase over a traditional backend I am a solo developer building a product that competes with companies backed by tens of millions. I cannot operate database clusters, manage migrations, handle connection pooling, and build features at the same time. Firebase gives me: Auth with email, Google, GitHub, Microsoft — zero custom code Firestore with realtime subscriptions — data changes propagate instantly t