I need an initial, working billing solution that runs smoothly on iOS, Android, and the web. The first release must cover the essentials for retail and hospitality businesses while leaving room to expand to nine or ten other sectors later. Core modules I want in this build: • Secure login with role-based access • Bill creation, editing, and deletion • One-tap PDF generation with WhatsApp share • Printable receipts • Customer / item record management with a searchable ledger • Basic credit tracking that shows outstanding balances per customer Data has to stay in sync across devices and remain available offline until a connection returns. A lightweight web dashboard should let me view, filter, and export all transactions. Tech stack is flexible—Flutter, React Native, Ionic, or similar for mobile; any modern web framework for the portal—so long as the APIs are RESTful and the code is clean and well-documented. Deliverables 1. Source code and build instructions for each platform 2. A short deployment guide so I can host it myself 3. A brief hand-off call or video walkthrough This is a functional prototype: keep the architecture modular so future features such as loyalty tools, analytics, and more business categories can slot in easily. Include a rough timeline and links to similar work you’ve shipped. I’m ready to start as soon as the right person comes along.