IoT Smart Locker System

The backend architecture and cross-platform mobile application for an IoT Smart Locker System, designed to facilitate secure, low-latency communication between mobile clients and ESP8266 microcontrollers. Built using Node.js, Express, MongoDB, and Flutter, this system manages user profiles, provisions embedded NFC card UIDs, and efficiently logs real-time access events via custom REST APIs and robust state management logic.

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🚀 Features

• Secure Remote Unlocking: Users can securely unlock their assigned lockers remotely from the mobile app via custom REST APIs.
• NFC Authentication Workflow: Supports physical NFC card tapping (Mifare RC522) with the ESP8266 microcontroller for instant physical access.
• Real-Time Access Logs: Comprehensive logging of all locker interactions (App Unlock, NFC Unlock, Admin overrides) stored efficiently in MongoDB.
• Admin Dashboard & Provisioning: Secure workflows for administrators to provision new users and assign NFC cards right from the app.
• Hardware Synchronization: Fault-tolerant communication logic between the Flutter frontend, Node.js backend, and the ESP8266 locker hardware.

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🛠️ Technology Stack

Backend / Infrastructure

• Node.js & Express.js
• MongoDB (Mongoose ORM)
• Custom RESTful APIs
• JSON Web Tokens (JWT) for secure authentication

Frontend / Mobile Application

• Flutter (Dart)
• Cross-platform support (Android / iOS)
• Provider for state management

IoT & Hardware

• ESP8266 Microcontroller
• C++ (Arduino IDE)
• RFID RC522 Module (for NFC unlocking)
• Relay Modules (for electronic lock actuation)

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📁 Repository Structure

IoT-Smart-Locker-System/
├── backend/            # Node.js, Express, and MongoDB backend code
├── frontend/           # Flutter cross-platform mobile application
└── firmware/           # C++ code for the ESP8266 and NFC modules

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⚙️ Getting Started

Prerequisites

• Node.js (v14+)
• MongoDB running locally or remotely
• Flutter SDK installed
• Arduino IDE (for flashing the ESP8266)

1. Backend Setup

cd backend
npm install
# Set up your .env file with your PORT and MONGO_URI
npm run dev

2. Frontend Setup

cd frontend
flutter pub get
# Update the API base URL in the frontend constants to point to your backend IP
flutter run

3. Firmware Setup

• Open firmware/esp8266_final/esp8266_final.ino in Arduino IDE.
• Update the Wi-Fi credentials (ssid and password).
• Update the backendUrl variable to point to your live backend server IP.
• Flash to your ESP8266.

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🤝 Contributing

Contributions, issues, and feature requests are welcome!

📝 License

This project is licensed under the MIT License.