Kanakku

Split trip expenses with a group. One shared link, no sign-up.

Next.js (App Router) + Postgres. Built for Vercel + Neon.

Deploy (about 5 minutes)

1. Push this folder to a GitHub repo.
2. On Vercel: Add New → Project, import the repo. Don't deploy yet.
3. In the project: Storage → Create Database → Neon. This creates the database and adds DATABASE_URL to the project for you. (If you already have a Neon project, add its pooled connection string as DATABASE_URL under Settings → Environment Variables.)
4. Deploy. Open the site, create the trip, share the link in your group chat.

There is no migration step. The app creates its tables the first time it connects (lib/db.ts).

On each phone: open the link, pick your name, then use the browser menu's "Add to Home screen" to install it like an app.

Run locally

cp .env.example .env.local   # paste a Postgres connection string
npm install
npm run dev
npm test                     # split and balance maths

How it works

• Access: a trip lives at /t/<16 random characters>. Anyone with the link can read and write, so share it only with the group. Each phone remembers who you are locally.
• Money is stored as integer paise. Balances are never stored; they are recomputed from the ledger every time (lib/balances.ts).
• Splits (lib/split.ts): equal, exact amounts, percent, shares, and by item. The server recomputes every split, so stored amounts always add up to the bill. Leftover paise go to the largest remainders, rotating between people across expenses.
• Kitty: contributions count as money paid in. Whoever holds the kitty is charged for what is left in it, so balances still sum to zero.
• People: someone with recorded expenses can't be deleted, only marked as left.
• History: every change is logged with who made it and what changed. Deleted expenses can be restored from the Group tab.
• Tickets: PDFs or photos (up to 20 MB each) of bus, train and flight tickets, entry passes and stay bookings. They are stored in Postgres and open full screen inside the app, with zoom and download. Vercel rejects any request or response over 4.5 MB, so files are uploaded and fetched in 2 MB pieces (ticket_chunks table, TICKET_CHUNK in lib/constants.ts). For PDFs, the type, route or venue, date, ticket number and passengers are read from the ticket's own text in the browser (lib/ticketParse.ts, written against redBus e-tickets). public/pdf.worker.min.mjs is a copy of node_modules/pdfjs-dist/legacy/build/pdf.worker.min.mjs; copy it again if you upgrade pdfjs-dist.
• Checklist (Plan tab, next to Tickets): things to bring. An item is either packed by everyone, each person ticking their own, or one for the group with a person bringing it. The Trip page shows what you still have left (lib/checklist.ts).
• Receipts are shrunk in the browser (about 150 KB each) and stored in Postgres.
• Sync: the page refetches every 6 seconds and on focus. Saves for one trip are serialised with a row lock, so simultaneous edits don't clash.

Layout

app/                    pages and API routes
  api/trips/[id]/       GET the whole trip, POST { action, actorId, payload }
components/             screens and forms
lib/split.ts            split maths          lib/balances.ts   balances + settle-up
lib/store.ts            validation, actions  lib/db.ts         schema + connection