Case study · 2026 · Full-Stack
Exsy — Family Money Book
An installable money app for a family: separate books per person, EMIs with GST, loans, a chit fund with fair draws, and entries filled in from a pasted bank SMS.
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01 The problem
At home, money is spread across people, accounts and notebooks: my own, my mother's and my father's, cash and three banks, card EMIs whose real cost hides in interest and GST, money lent to relatives, and a chit fund run from a notebook. Generic expense apps track one person's spending and can't answer the questions that matter here: whose money is whose, who still owes, and what an EMI really costs.
02 Approach
- 01
Books keep each person's money apart, each with its own cash, bank, investment and card accounts. Balances are never stored: they're derived from the entries, so they can't drift.
- 02
EMIs on the reducing-balance method, with GST on each month's interest and on the processing fee; each month's bill is added to the card on its due date.
- 03
A chit fund manager: monthly collection grid, overdue list, a random draw among members who haven't won yet, payout minus commission, and statements.
- 04
Paste a bank SMS or UPI message and the entry fills itself: amount, direction, account (by bank name or last 4 digits), date, and the person, chit member or shop.
03 Architecture
04 Results
- Live on GitHub Pages and installable on Android from the browser; a Google Play release is being prepared.
- Every entry explains itself in plain words, with balances before and after, e.g. "Gulshan's Cash: ₹16,540 → ₹19,540".
- Each person's data is private to their Google account, enforced by Firestore security rules rather than by the app.
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