Expense Splitter

A backend REST application to manage trips, participants, expenses, and settlements.

What this project does

This project lets users:

• create and manage trips
• add participants to a trip
• record trip expenses
• view all recorded transactions
• compute settlements between participants
• compute both:
  • basic settlement — direct balances
  • simplified settlement — reduced number of payments
• persist all state in PostgreSQL so the service survives restarts

Project structure

• expense-splitter.standalone — core Java domain and settlement logic
• expense-splitter.webservice — Spring Boot REST API and persistence layer

Tech stack

• Java
• Spring Boot
• PostgreSQL
• Maven
• Docker / Docker Compose

Notes

• This is a backend-only application.
• There is no frontend/UI in this repository.
• Settlement state is persisted and recomputed when transactions change.

Getting started

To run the application locally, please go directly to:

START-WITH-ME.md

That file contains the deployment steps, setup flow, and commands needed to start the application.

Documentation

Additional project notes and supporting documents can be placed under the docs/ folder.