Receipt Rivulet is a budgeting app designed for managing cash-envelope spending. Users can create cash envelopes to allocate funds for different categories of spending. The app allows users to track their weekly expenses by capturing real receipts. Users can input the amounts spent from each envelope as they make purchases. The app provides an interface to view current envelope balances. Users can set rules for rolling over unused funds to the next week. The app helps users visualize their spending habits and manage their budgets effectively. Overall, it offers tools for organizing and monitoring personal finances through a cash envelope system.