Convert Mobile Health App to PWA

We are seeking an experienced developer to convert a complete working mobile health app (HTML) into a Progressive Web App. The project involves implementing user accounts and integrating cloud storage to ensure seamless data management. The app should be compatible with both iOS and Android platforms. The ideal candidate will have a strong background in web development and a keen eye for detail to ensure a smooth transition and high-quality user experience. BUDGET: $1,500 – $3,000 (fixed price) TIMELINE: 4–6 weeks --- THIS IS A MOBILE APP PROJECT I have a fully built, fully functioning mobile HTML app called ProteIn50 — a high protein diet and daily food tracking app designed specifically for adults over 50. The app works right now in Chrome and Safari on iPhone and Android. Every feature is complete and tested. Your job is NOT to design or build the app from scratch. The app is done. Your job is to convert it into a Progressive Web App (PWA) that users can install to their phone home screen, with real user accounts, cloud data storage across devices, and a one-time payment of $24.99 before account creation. --- THIS IS A MOBILE-FIRST APP — NON-NEGOTIABLE REQUIREMENTS - Must install to iPhone and Android home screen like a native app - Must work perfectly on phone screens 375px–430px wide — this is the primary use case - Must work on iOS Safari and Android Chrome - All buttons and touch targets must be finger-friendly (minimum 44px) - Must load fast on mobile internet - Core features must work offline when there is no internet - Must feel like a real app, not a website on a phone --- WHAT THE APP ALREADY INCLUDES — ALL COMPLETE AND WORKING - Protein and calorie calculator personalized by weight, age, sex, activity level, and goal - 28-day interchangeable meal plan — tap Swap to change any meal on any day, tap Log to add to tracker - USDA Foundation Foods database search — real-time nutritional data, whole foods only, no brand names - Manual food entry — user types exactly what they ate, enters protein and calories (e.g. 4 egg whites fried, no butter — 14.4g protein, 80 calories) - Daily food tracker with protein progress ring, calorie bar, food log organized by meal, and 7-day weekly summary - One-tap beverage logging — 8 common drinks pre-loaded, plus custom beverage entry - Saved favorites — foods and beverages saved once, logged in one tap every time after - 7-day grocery list builder with checkboxes and print function - Snack guide — 7 protein + fruit combinations, tap any to log instantly - Fruit guide — best fruits for adults over 50 with protein pairings - 21 complete recipes organized by breakfast, lunch, and dinner — tap View for instructions, tap Log to add to tracker - All data saves locally between sessions - Navigation built with CSS radio buttons — works without JavaScript, compatible with all mobile browsers --- WHAT I NEED YOU TO BUILD 1. Convert the HTML file into a Progressive Web App installable on iPhone and Android home screen 2. PWA manifest and service worker for offline capability and home screen icon 3. User account system — sign up, log in, reset password via email 4. Cloud database so user profiles, food logs, favorites, and meal swap choices sync across all devices in real time 5. Stripe payment — users pay $24.99 once before creating their account 6. Home screen app icon and splash screen for both iPhone and Android 7. Simple admin dashboard — I need to see total registered users and basic usage 8. Must pass Google Lighthouse mobile audit score of 85 or higher --- TECHNOLOGY REQUIREMENTS - Frontend: React or your recommended framework — preserve existing CSS and layout - Backend / Auth / Database: Supabase (preferred) or Firebase - Payments: Stripe - USDA FoodData Central API already integrated in the prototype - Hosting: Vercel or Netlify - The existing CSS radio button navigation must be preserved or replaced with something equally reliable on mobile --- WHAT I WILL PROVIDE - The complete working HTML file — every screen, feature, design, and piece of content is finished and tested - All 21 recipes, 28-day meal plan, grocery lists, snack guide, and fruit guide already written - USDA API already integrated and functioning - Clear written specification of every feature - Prompt communication and feedback throughout --- IDEAL CANDIDATE - Has built and published at least one PWA that installs to a phone home screen — please provide a link - Portfolio showing a completed health, fitness, or nutrition app - Strong experience with Supabase or Firebase authentication and real-time database - Experience with Stripe payment integration - Understands mobile UX — knows what makes an app feel right on a phone screen - Communicates clearly in plain English, not technical jargon - Available to start within 2 weeks - Upwork rating 4.8 stars or higher with 10 or more completed jobs --- PAYMENT STRUCTURE — UPWORK MILESTONES - 30% on project start - 40% when the app installs to my iPhone and Android with user accounts and sync working - 30% on final delivery — live, fully tested, payment processing active --- TO APPLY — all four required or your application will not be reviewed 1. A link to a PWA or mobile web app you built that installs to a phone home screen 2. Whether you recommend Supabase or Firebase for this project and why 3. Your estimated timeline 4. Your fixed price bid