A development team shares their experience building large-scale enterprise frontends and the recurring pain points they encountered: poor performance, lack of modularity, vendor lock-in, and tight coupling between frontend and backend systems. To address these challenges, they created Open Self Service (O2S), an open-source framework for composable frontend applications focused on customer portals and digital platforms. The framework includes Next.js-based foundations, reusable UI components, backend integration layers, and application starters to help teams build faster while avoiding common architectural pitfalls.