Paper Invoice
Offline-first iOS invoice app built with React Native and Expo in just 7 days, helping contractors and freelancers create professional PDF invoices in 30 seconds. Features complete privacy with device-only data storage and gained 37 users in the first week after launch.
The Problem
Contractors and freelancers face challenges with traditional invoicing tools: they're time-consuming, require constant internet connectivity, upload sensitive data to cloud servers, charge monthly subscriptions, and often include unnecessary complexity. Most people want a simple, fast, and private way to create professional invoices without the overhead.
My Solution & Technical Details
I built Paper Invoice as an offline-first iOS app that enables invoice creation in ~30 seconds with complete privacy. The app stores all data locally on the device (never uploaded to servers), requires no account or internet connection, and features a streamlined workflow with saved rates and client management. Built in just 7 days using React Native and Expo, it launched on the App Store with a one-time purchase model.
Key Technical Implementations:
- Built with React Native and Expo for rapid mobile development (7-day timeline)
- Implemented TypeScript throughout for type safety and code quality
- Used React Native Paper for Material Design UI components
- Created offline-first architecture with AsyncStorage for local data persistence
- Implemented custom PDF generation for professional invoice output
- Designed streamlined UX workflow to achieve 30-second invoice creation
- Built client management system with saved hourly rates for quick access
- Added invoice status tracking (draft, sent, paid)
- Implemented flexible sharing via email, AirDrop, Messages, and file export
- Created custom branding features for business logos and personalization
- Ensured complete privacy with device-only storage and zero tracking
- Published to iOS App Store with one-time purchase monetization model
Project Screenshots
Invoice list view showing draft, sent, and paid invoices with status indicators for easy organization
Create new invoices completely offline with client selection, due dates, and line items
Settings screen with branding customization, business credentials, and payment method options
Professional invoice preview with share button for email, text, AirDrop, or file export
My Rates view with saved hourly rates for quick invoice creation and recurring clients
Outcomes & Results
- Successfully launched production iOS app in just 7 days from start to App Store
- Achieved 37 user acquisitions organically in the first week without marketing
- Delivered 30-second invoice creation target with streamlined UX
- Implemented true offline-first architecture with complete privacy
- Created professional PDF generation suitable for business use
- Built sustainable business model with one-time purchase ($39.99)
- Demonstrated rapid MVP development using React Native and Expo
- Validated product-market fit with strong early user adoption
AI Integration & Code Implementation
🔧 API Implementation Details
Endpoint
N/A (Offline-first mobile app)Error Handling
Local error handling with user feedback
Caching Strategy
Device-only AsyncStorage persistence
💡 Prompt Engineering
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