A calendar-based household account book app is a tool that allows users to integrate schedule management and financial management, with the following key features and characteristics:

Intuitive Calendar Interface
Visualize income and expense items in monthly/weekly calendar views, distinguishing expense types with color codes

Manual Text Input System
Minimal UI design for direct keyboard input of amount/category/memo. Includes quick recording feature in the format of 'Food 15,000 won #lunch'

Semi-Automation
Automatically register periodic bills (utilities, rent) on a monthly basis when set

Real-time Balance Projection
Calculate future account balances by date based on registered transactions

Data Visualization Reports
Analyze monthly spending patterns with pie charts and bar graphs

Budget Setting and Monitoring
Allocate monthly budgets by category and display warnings when overspending

Search Filter System
Extract specific period/category history with searches like 'July 2024 ~ January 2025 #cafe'

Receipt Image Attachment
Manage transaction evidence through camera capture/gallery selection

Flexibility in Settings
User-defined month start date (1st/5th/25th)

Backup and Recovery
Local backup

Widget Functionality
Check daily spending status with home screen widget

Offline Mode
Use basic functions without internet connection