README.md

🎮 Fusion2048 – Full Stack Web Application

Fusion2048 is a production-ready full-stack web application built using Spring Boot and PostgreSQL with manual JWT-based authentication and a vanilla JavaScript frontend. The system implements secure stateless authentication, persistent score storage, and layered backend architecture.

🌐 Live Application

https://fusion2048.vercel.app/

🏗 System Architecture

flowchart TD

A[Frontend<br>HTML CSS JS] -->|REST API| B[Spring Boot Backend]

B --> C[Security Layer<br>JWT Filter]
C --> D[Controllers]
D --> E[Services]
E --> F[Repositories]

F --> G[(PostgreSQL)]

Loading

🔐 Authentication Flow (Manual JWT Implementation)

1. User submits login credentials
2. Password validated using BCrypt
3. JWT token generated using secret key
4. Custom JWT filter intercepts every request
5. Token validated before accessing protected endpoints
6. Stateless authentication

🚀 Tech Stack

Frontend

HTML CSS JavaScript

Backend

Java Spring Boot Spring Security Custom JWT Filter JPA / Hibernate

Database

PostgreSQL (Render)

Deployment

Frontend deployed on Vercel
Backend & PostgreSQL deployed on Render
Environment variables for secrets

📡 Core Features

User Registration
Encrypted Password Storage (BCrypt)
Manual JWT Authentication
Stateless Session Management
Persistent Score Tracking
RESTful API Architecture
Production Deployment

🗄 Database Schema Overview

User id username (unique) password (encrypted)

Score id user_id (foreign key) score timestamp

⚙️ Run Locally

Backend
mvn clean install
mvn spring-boot:run

frontend
Open index.html

📸 Application Screenshots