An application exists that has been designed for managing expenses associated with group trips and ongoing shared accommodations. This app operates on multiple platforms using a single codebase via Flutter, covering Android, iOS, macOS, Windows, Linux, and web applications. The backend is powered by FastAPI with PostgreSQL. At the heart of the app is a robust settlement engine which ensures fair expense distribution among group members. It effectively reduces group balances into minimal payments required for settling, avoiding the need for manual calculations. Additionally, it organizes recurring expenses by allowing balances to be carried forward between billing periods. The app supports email and phone number authentication with JWT-based sessions, ensures security with ownership checks, and offers report generation in PDF and Excel formats. Joining a group is simplified by the use of 6-character codes and QR scans, and the interface maintains a consistent design, adaptable to both light and dark modes. The app’s backend, protected by authentication, comprises numerous routes backed by a comprehensive testing suite, ensuring the effectiveness of the settlement engine against various edge cases. This project represents a complete, market-ready product available for purchase at the source-code and intellectual property level, with no current live users or revenue. There are some limitations, such as manual updates instead of live push notifications and static API configurations, all of which are disclosed upfront. Included in the sale are the full source codes, branding assets, deployment configurations, and comprehensive technical documentation, presenting an ideal opportunity for developers to refine and take the app to market.