I run a small service business and need an Android app that allows people to book appointments in the quickest, most friction-free way possible. The first release is intentionally lean: a customer opens the app, selects one of the pre-defined open slots and confirms the booking. The booking details reach the service provider instantly, while an admin panel (web or in-app) lets me adjust schedules and manage users. Three distinct roles must exist from day one—Customer, Service Provider and Admin—each seeing only the screens and actions relevant to them. Customers only book; providers receive and acknowledge bookings; admins create, edit or block time slots and users. No cancellations or chat features are required right now, but the architecture should leave room to add them later. I’m flexible on tech as long as the first build is a Play-Store-ready APK. Flutter, React Native, Kotlin or even native Java are all fine if the codebase can later compile to iOS with minimal rework. A lightweight back-end such as Firebase, Supabase or a small Node/Express API will do, provided it stores bookings securely and enforces role-based access. Deliverables • Production-ready Android APK (plus Play Store bundle) • Full source code with README • Deployed back-end (or detailed setup guide) • Short hand-off video or call explaining how to add slots and providers Acceptance Criteria • A customer can select a free slot and receive an in-app confirmation • The service provider is notified in real time • The admin view updates instantly and shows the new booking