Shonchoy

Inspiration

Shonchoy (সঞ্চয়) means savings in Bangla. Women in Bangladesh often manage the household money. Many have irregular income and a microloan at 20–45% interest. Most finance apps are in English, full of jargon, and built around a steady salary. We wanted a warm, private, bilingual money planner that fits how these women actually live.

What it does

Onboarding: an 18+ checkbox (no age stored), then income setup: monthly, yearly or irregular, with multiple sources.
Money: fixed and variable expenses, plus debts with warnings for high interest and for a high share of income going to debt. A payoff slider shows how paying more shortens a loan.
Plan: an automatic monthly budget. After expenses and debt, the rest is split between an emergency fund, goals and flexible spending.
Goals: an emergency fund tracker, custom goals with a live timeline slider, and investment guidance that is educational only.
Home & Learn: a health score out of 100, personal insights, 8 plain-language lessons and a scam red-flag checker.
EN | বাং toggle on every screen.

How we built it

Plain HTML, CSS and JavaScript with no framework and no build step. It's deployed from GitHub to Vercel/Netlify, and all data stays in the browser. Three shared pieces keep the team consistent:

one data schema that every screen reads and writes
one calculation engine, computePlan(), with unit tests
one dictionary holding every string in English and Bangla

The budget works like a waterfall:

$$ L = \max!\left(0,\; I - E - \textstyle\sum_j m_j\right) $$

$I$ is monthly income, $E$ is expenses and $m_j$ are the minimum loan payments. The leftover $L$ is split 60/20/20 while the emergency fund is under half full, then 40/35/25, then 0/65/35 once it's full. Loan payoff time uses the standard loan repayment formula:

$$ n = \left\lceil \frac{-\ln!\left(1 - \frac{rB}{P}\right)}{\ln(1+r)} \right\rceil $$

$B$ is the balance, $r$ the monthly interest rate and $P$ the monthly payment. The emergency fund target is 3 months of essential costs, or 6 if income is irregular.

Challenges we ran into

Bangla done properly: we needed fonts that cover both scripts, taller line spacing, Bangla digits, and South Asian number grouping (১,০০,০০০).
Edge cases in the maths: when a payment is less than the monthly interest ($P \le rB$), the loan never ends. We had to catch that case instead of showing a broken number. We also had to stop the plan from putting more into an emergency fund that was nearly full.
Keeping the team's schema unchanged while still adding a dropdown for the income source type.
Helpful but not financial advice: the investment guide gives general rules, never product picks.
Live sliders that update instantly without the screen losing focus.

Accomplishments that we're proud of

The whole app works fully in English and Bangla, including numbers and dates.
The health score is easy to understand: it's five visible parts, not a black box.
The design is privacy-first: no accounts, no server, and no age stored.
A petal-edged coin logo and a pink-and-plum design system shared across every teammate's screen.
The layout works on phones, with tested calculations and a live demo.

What we learned

Explaining where a number comes from builds more trust than a clever number with no explanation.
Design for edge cases first, because real users hit them on day one.
Supporting a language well affects fonts, spacing, number formats and tone.
Shared conventions let a team build separate screens that still fit together.

What's next for Shonchoy

Have native speakers review the Bangla copy, and test the app with community groups.
Make it installable and usable offline.
Add monthly check-in reminders.
Add savings history charts.
Offer optional, opt-in sync between devices.