The Rails SaaS Architecture I Wish I Had 5 Years Ago

The Rails SaaS Architecture I Wish I Had 5 Years Ago Five years ago, I started building SaaS applications with Ruby on Rails. Like most Rails apps, everything started beautifully simple. A few models. A few controllers. Some concerns. Some service objects. It felt clean. Six months later? Business logic everywhere “Temporary” modules that became permanent Cross-cutting features tangled across the app Shared helpers doing too much Growing fear of refactoring core features The app still worked — but the architecture wasn’t intentional anymore. And that’s the real problem. The Pattern I Kept Repeating Every SaaS I built ended up having the same core capabilities: Authentication Roles & permissions Notifications Audit logs Dashboards Support tickets Document management Account scoping / multi-tenancy But I kept rebuilding them inside the main app. Every. Single. Time. And every time, they slowly leaked into everything else. The Architecture Shift At some point I started asking myself: What