Split & Settle 💸

A full-stack expense splitting application that calculates the minimum number of transactions to settle group debts.

🚀 Features

• JWT-based authentication (register & login)
• Create groups and invite members by email
• Add shared expenses with automatic equal splitting
• Debt simplification algorithm to minimize settlements
• RESTful API with Swagger documentation

🛠️ Tech Stack

Layer	Technology
Frontend	Angular 17, PrimeNG, TypeScript
Backend	Spring Boot 3, Spring Security, JWT
Database	MySQL 8
Build	Maven, npm

📁 Project Structure

split-settle/ ├── api/ # Spring Boot backend ├── split-settle/ # Angular frontend (in progress)

⚙️ Backend Setup

Prerequisites

• Java 17+
• MySQL 8+
• Maven 3.8+

Steps

# Create database
mysql -u root -p
CREATE DATABASE splitsettle;

# Run the backend
cd api
mvn clean install
mvn spring-boot:run
# API runs at http://localhost:8080
# Swagger UI at http://localhost:8080/swagger-ui.html

📡 API Endpoints

Method	Endpoint	Description	Auth
POST	/api/auth/register	Register user	No
POST	/api/auth/login	Login	No
GET	/api/groups	Get my groups	Yes
POST	/api/groups	Create group	Yes
POST	/api/groups/{id}/members	Add member	Yes
POST	/api/expenses	Add expense	Yes
GET	/api/expenses/group/{id}	List expenses	Yes
GET	/api/settlements/{groupId}	Get settlements	Yes
POST	/api/settlements/settle	Settle up	Yes

🧮 Debt Simplification Algorithm

Instead of tracking every individual debt, the app calculates each user's net balance (paid - owed), then uses a greedy algorithm to match the largest debtor with the largest creditor — minimizing total transactions needed to settle a group.

🔒 Security

• Passwords hashed with BCrypt
• Stateless JWT authentication
• CORS configured for local frontend dev

📸 Screenshots

(Coming soon — frontend in progress)

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Built by Dinesh Ravi