Device Guardian
The Challenge
The challenge was to build a foolproof device financing security platform that enforces automatic EMI locks, remote admin controls, and real-time telemetry. We needed a robust architecture capable of handling offline edge-cases, SIM swaps, and tampering attempts, all while providing a flawless user experience across a massive network of retailers.
Role
Product Strategy
Mobile Engineering
Backend Architecture
Platform
Flutter (Android/iOS)
Next.js Dashboard
Laravel API
Frontend & Mobile
Flutter, React, Next.js
Backend
Laravel REST API, Node.js
Infrastructure
MySQL, Firebase Cloud Messaging
Core Features
Automatic EMI Lock
Every installment has a due date and lock date. Missed payments trigger a full-screen kiosk lock, rendering the phone unusable except for emergency calls. Reminders are pushed before the lock date.
Instant Remote Control
Retailers and admins can lock or unlock any device in one tap via Firebase push commands. Includes offline fallback using one-time unlock codes.
Tamper Resistance
Installed as Device Owner, preventing uninstallation. Features factory-reset and SIM-swap detection with automatic re-lock and alerts.
Payment & EMI Integration
Flexible installment engine automatically generates schedules. Retailers can mark payments as received, instantly unlocking the device.
Device Analytics & Tracking
Periodic GPS location reporting with history. Real-time telemetry ensures IMEI validation and monitors device and SIM status continuously.
The Problem
Retailers and finance companies sell smartphones on installments (EMI), but have no control after handover. Customers stop paying and keep using the device — recovery is slow, costly, and often impossible. Common bypass tactics defeat naive lock apps: Factory reset / flashing the ROM to remove the lock app, Swapping the SIM card to escape tracking, Uninstalling or force-stopping the control app, Selling the phone on the second-hand market while EMIs are unpaid. Result: default rates of 15–30% on device financing in emerging markets, killing retailer margins. Manual follow-up (calls, visits) does not scale beyond a few hundred customers.
Our Solution — Device Guardian
A complete device-financing protection platform. If the customer doesn't pay, the phone locks itself — automatically, on the EMI schedule. Everything is synchronized in real time through a central cloud backend with push notifications (Firebase).
How It Works
1. Sell & Enroll
Retailer registers the customer, scans IMEI, installs the Guardian app as Device Owner.
2. EMI Plan Created
Backend generates the full EMI schedule with due dates and automatic lock dates.
3. Monitor
Device reports status, SIM details and location; dashboard shows the whole portfolio.
4. Auto-Lock on Default
Missed payment -> kiosk lock screen with amount due. Reminders pushed before due date.
5. Pay & Unlock
Payment marked (or code entered) -> instant remote unlock. Fully paid -> app self-removes.
Architecture
Customer App (Flutter)
Device Owner, Kiosk lock, FCM
Retailer App (Flutter)
Customers, EMI, Lock control
Admin Dashboard (Next.js)
Reports, Users, Settings
Laravel REST API
EMI engine, IMEI validation, Credits, Notifications
MySQL Database
Customers, Devices, EMIs, Logs
Firebase Cloud Messaging
Push lock/unlock & reminders