GPS Tracking & Accounting System

I need a full-stack solution that lets both individual customers and corporate clients monitor vehicle pick-ups and drop-offs in real time while keeping every rupee of the operation balanced in one place. The system must be available on the web and as companion mobile apps so users, drivers, and back-office staff can work seamlessly from any device.

Key modules I must see at launch:
• Real-time GPS tracking – live map refresh, breadcrumb history, geofence alerts
• Service charge calculation – automatic fare generation based on distance, time, or custom tariff tables
• Detailed accounting reports – trip-level ledgers, monthly P&L, GST-ready invoices, export to Excel/PDF

Beyond those essentials, the workflow should cover trip scheduling, driver assignment, customer notifications, and secure online payments so that the moment a ride finishes both the customer and I can see the charge and it instantly reconciles in the books.

Deliverables
1. Responsive web portal for admins, dispatchers, and business clients
2. Android & iOS apps for drivers and end users, published to the stores under my accounts
3. RESTful API and database schema documentation
4. Source code hand-over with build/run instructions

Acceptance criteria
• Map position updates no slower than every 5 seconds
• Fare shown to user matches ledger entry 100 % of the time
• All reports export without data loss or column shift

If you already have experience with GPS SDKs (Google Maps, Mapbox), Flutter or React Native, and solid accounting-module builds, tell me how you would structure the database for trips versus ledger entries and what tech stack you prefer for scalability.