Splitify - Backend (Java Spring Boot)

https://splitify-java-backend.onrender.com

Splitify is a smart expense-splitting backend API built using Spring Boot. It allows users to create groups, split expenses with friends, track who owes whom, and settle transactions. JWT-based authentication and Spring Security are used to secure endpoints.

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📚 Features

• ✅ User Signup/Login with JWT Authentication
• ✅ Secure endpoints with Spring Security
• ✅ Create and manage expenses
• ✅ Split expenses between participants
• ✅ Track balances: who owes whom
• ✅ Friend management
• ✅ Group support (optional)
• ✅ MongoDB with DBRef or manual references for users & expenses
• ✅ LLD-compliant modular structure

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📌 Tech Stack

• Java 17+
• Spring Boot
• Spring Security
• JWT (JJWT 0.11.x)
• MongoDB
• Maven
• Lombok

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🏗️ Project Structure

• /src/main/java: Contains the Java source files for the application.
• /src/main/resources: Contains the configuration files like application.properties.
• /src/test: Contains unit and integration tests.
• Dockerfile: Defines the Docker image to run the application in a containerized environment.
• pom.xml: The Maven project descriptor file that manages project dependencies and build lifecycle.

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🚀 How to Run

Locally:

1. Clone the repository.
2. Install the dependencies:

   mvn install

3. Run the application:

   mvn spring-boot:run

4. Open http://localhost:9090 to access the API.

With Docker:

1. Build the Docker image:

   docker build -t splitify-backend .

2. Run the container:

   docker run -p 9090:9090 splitify-backend

3. Open http://localhost:9090 to access the API.

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🔑 Authentication

This application uses JWT (JSON Web Tokens) for user authentication. When you log in or sign up, you'll receive a token to include in the Authorization header for accessing protected endpoints.

Example:

Authorization: