GPS Geofencing
Validate attendance based on configured work locations.
Case Study
Bijelic TimeTrack
Production Workforce Management Platform
Bijelic TimeTrack is a full-stack employee time tracking platform built from scratch for real-world workforce management.
The Problem
Traditional employee time tracking can become difficult to manage when attendance, work locations and reporting need to be handled across multiple employees and locations.
The system was designed to provide digital check-in/check-out, location-aware attendance, centralized administration, reporting and reliable operation even when connectivity is unavailable.
The Solution
TimeTrack combines a Flutter frontend, Spring Boot backend and PostgreSQL database into a complete full-stack production application. The system includes JWT authentication, role-based access, GPS geofencing, NFC check-in/check-out, offline synchronization, PDF reporting and multilingual support.
Key Features
NFC Attendance
Use NFC cards for fast site-based check-in and check-out.
Offline-First Workflow
Store attendance actions locally when connectivity is unavailable and synchronize them when the connection returns.
Role-Based Access
Separate employee and administrator capabilities.
Reporting
Provide today, week and month reporting together with PDF export.
Multilingual UI
Support English, German, Bosnian, Serbian and Croatian.
Administration
Manage users, sites and attendance-related data through the administration interface.
Authentication
Secure API access using JWT authentication and refresh tokens.
Architecture
Application Flow
Flutter
↓
REST API
↓
Spring Boot
↓
PostgreSQL
Production
Docker
↓
Nginx
↓
Linux VPS
The application uses a Flutter frontend communicating with a Spring Boot REST API. PostgreSQL provides persistent storage, while Docker containers are used for production deployment behind Nginx on a Linux VPS.
Authentication & Security
- JWT authentication for secure session handling
- Access tokens for authenticated API requests
- Refresh tokens for session continuation
- Role-based authorization for protected capabilities
- Protected API endpoints for secured backend access
- Secure HTTPS production deployment
Offline-First Attendance
Attendance should not depend entirely on an active internet connection.
User performs Check-In / Check-Out
↓
Connection available?
↓
YES
Send to API
NO
Store locally
↓
Connection restored
↓
Synchronize pending actions
GPS location and site selection are handled as part of the offline workflow so attendance operations can continue reliably.
NFC Site Check-In
NFC card
↓
Read site identifier
↓
Select corresponding site
↓
Perform check-in/check-out
The application supports NFC-based site identification as part of the attendance workflow.
GPS Geofencing
Geolocation is used to validate whether an employee is within an allowed work-site area before attendance actions are accepted.
Administration
- User management
- Site management
- Employee management
- Attendance and reporting visibility
- Role-based access
Reporting & Export
- Today reports
- Weekly reports
- Monthly reports
- Work history
- PDF export
Technology Stack
Backend
Java • Spring Boot • Spring Security • REST API • JWT
Frontend
Flutter • Dart • Android • iOS • Web
Database
PostgreSQL • JPA • Hibernate
Infrastructure
Docker • Linux • Nginx • VPS • SSL
NFC
NFC integration
Location
Geolocation • GPS Geofencing
Engineering Challenges
Offline synchronization
Attendance needs to remain usable when connectivity is unavailable.
NFC integration
Integrating NFC-based site identification into the attendance workflow.
Geolocation
Validating attendance against configured work locations.
Authentication
Protecting API endpoints while supporting access and refresh tokens.
Production deployment
Running the complete application stack using Docker, Nginx and a Linux VPS.
Production Deployment
Docker
↓
Backend • Frontend • PostgreSQL
↓
Nginx
↓
HTTPS
↓
timetrack.mmtrvc.de
The application is deployed to a Linux VPS using Docker containers and exposed through HTTPS.
Screenshots
What Was Built
- Full-stack workforce time tracking application
- Cross-platform Flutter frontend
- Spring Boot REST backend
- PostgreSQL persistence layer
- NFC attendance integration
- GPS geofencing
- Offline synchronization
- Role-based administration
- Reporting and PDF export
- Docker-based production deployment
Try the Live Demo
Explore the production application and experience the workflow directly.
Open Live Demo