DEV Community: Bishnu Saha

I Built a Bilingual Profit Tracker for My Father's Cyber Café — Here's the Stack and a Few Decisions Behind It

Bishnu Saha — Mon, 06 Jul 2026 12:01:35 +0000

My father runs a cyber café — one of the small service shops across India (CSCs, cyber cafés, Xerox/DTP counters) that resell government or utility services: Aadhaar updates, PAN cards, printing, bill payments, exam forms. The business model is simple: charge the customer a fixed fee, pay a smaller cost to the portal/vendor that actually processes it, keep the difference.

The problem is just as simple, and just as easy to miss: he could always tell you how much cash came in for the day. He could almost never tell you how much of that was actually profit, because that means subtracting a different portal cost for every single service, every single transaction, in his head, at the end of a long day.

So I built Khata ("ledger" in Hindi/Bengali) to do that subtraction for him, automatically, per transaction, in real time.

What it does

Define each service once — name (English/Hindi/Bengali), an emoji icon, a default customer charge, and a default portal cost
Log a transaction in two taps: pick the service, the charge/cost pre-fill, adjust quantity if it's a bulk job (e.g. 100 photocopies in one entry instead of 100 separate rows)
Dashboard shows today's profit, collections, cost, and transaction count at a glance
Reports over today/week/month/custom range with a 7-day profit trend chart
Expense tracking (rent, electricity, stationery) separate from service transactions
Full UI in English, Hindi, or Bengali
The stack
Frontend: React + Vite + TypeScript + Tailwind, i18next for the three locales
Backend: Node.js + Express + TypeScript
Auth: JWT in a signed httpOnly cookie — no client-side token handling at all
Database: Postgres via Supabase, but only ever touched from the backend
A couple of decisions worth mentioning
RLS as a deny-by-default wall, not a per-row policy engine. Every table has Row Level Security enabled with zero policies for anon/authenticated. That's deliberate — RLS-enabled-with-no-policies denies all access by default. The backend connects with the service_role key, which bypasses RLS entirely. So the frontend has literally no path to talk to the database directly, and I didn't have to hand-write a policy for every table/role combination. The backend derives shop_id from the session cookie on every request and scopes every query to it, which is the actual multi-tenancy boundary.

Money math lives in the request path, not the UI. profit is a Postgres generated column (customer_charge - cost_paid), computed once, at the source of truth, instead of every consumer re-deriving it (and risking drift between the dashboard, reports, and the table view).

Quantity as a multiplier, not a loop. Early on the only way to log "100 photocopies" was 100 identical rows. Adding a quantity field that scales charge/cost while staying overridable (for discounts or one-off pricing) removed almost all the friction my father actually complained about.

i18n wasn't a layer bolted on later. Every service name, every label, is stored/rendered per-language from day one, because the actual users of this app are far more comfortable in Hindi or Bengali than English — an assumption a lot of small-business tools targeting India get backwards.

Try it
It's live and free: https://khata-ebon.vercel.app/

Built for one cyber café, but the shape of the problem (charge vs. cost, per transaction, in a language you actually think in) applies to a lot of small shops. Happy to answer questions about any of the above, especially the RLS/multi-tenancy setup — curious how others have handled a similar "backend-only DB access" pattern with Supabase.

I built a personal expense tracker because I kept lying to myself about money

Bishnu Saha — Mon, 29 Jun 2026 07:17:47 +0000

I'm bad with money. Not "forgot to save" bad — "spent ₹4,000 on food delivery in
one week and convinced myself it was fine" bad.

I tried spreadsheets. I tried apps. Nothing stuck. Either too complex, too ugly,
or needed a subscription for features that should be free.

So I built Spendly. A simple, fast expense tracker that actually fits how I think
about money.

What it does

Log expenses in under 10 seconds
Organise by category with custom icons and colours
Track a monthly budget and see exactly where you're over
Set savings goals with a visual progress ring
Recurring expenses that auto-log themselves daily
Income sources (freelance, salary, side projects)
Dark mode, because obviously

It's live at spendly.it.com — free, no credit card.

The stack

Frontend: React + Vite, deployed on Vercel
Backend: Express + Prisma, deployed on Render (free tier)
Database: Supabase (PostgreSQL)

Boring and correct. The free tier combo of Render + Vercel + Supabase means
$0/month to run.

The bugs that taught me things

The timezone nightmare

I built a "salary cycle" feature — expenses reset on whatever day your salary lands,
not on the 1st of the month. Smart idea. Terrible execution the first time.

My getCycleRange() helper was mixing local time and UTC. The client (IST, UTC+5:30)
would compute cycleStart and send it as an ISO string. The server, running UTC,
would parse it and quietly shift into the previous month. Result: empty expense lists
in production, everything working perfectly in local dev.

Fix: use UTC methods everywhere, consistently.

I Built a Free Expense Tracker Because I Was Terrible With Money

Bishnu Saha — Wed, 17 Jun 2026 14:26:06 +0000

I used to check my bank balance at the end of every month and just stare at it.

Good salary. Nothing saved. No idea where it went.

I tried spreadsheets. I tried Mint. I tried YNAB. Every app was either too complex, too expensive, or just not something I'd actually open every day.

So I built my own.

What is Spendly?
Spendly is a free, clean monthly expense tracker built for people who just want to know where their money goes — without learning a new system.

No bank account linking. No subscription. No complexity.

Just: open it, add an expense, close it.

Live: https://spendly.it.com

What it does
Add and categorize daily expenses in seconds
Set a monthly budget and track it in real time
Visual donut chart — breakdown by category
Cycle history bars — compare spending month over month
Savings goals tracker
Dark mode
Works on any device — no installation needed

Tech stack

Frontend — React + Vite, deployed on Vercel

Backend — Node.js + Express + Prisma, deployed on Render

Database — PostgreSQL via Supabase

Auth — JWT stored in localStorage

The hardest bug I fixed
The most frustrating bug was a timezone mismatch in production.

My cycle helper was using local time methods (new Date(year, month, day)) on the client. But the server runs in UTC. So when I was in IST (UTC+5:30), the client sent a cycleStart ISO string that the server mis-parsed into the previous month — returning zero expenses every time.

Fix: use UTC methods everywhere (getUTCFullYear, getUTCMonth, Date.UTC()) on both client and server.

Lesson: always use UTC in production. Local time will betray you.

What I learned building this
Free tiers (Vercel + Render + Supabase) are genuinely powerful for solo projects
Render cold starts on free tier are real — first load takes 30-50 seconds
Prisma auto-camelCases column names — monthly_budget becomes monthlyBudget in JS
Building for yourself first makes product decisions 10x easier

What's next
Mobile app (React Native)
Recurring expenses
Export to CSV
Email summary every month

Try it
https://spendly.it.com

It's completely free. No ads. No premium tier. No credit card.

I'm at about 10 users right now and genuinely want honest feedback — what would make you actually use an expense tracker every single day?

Drop a comment — I read every one.