Splibilo

Track shared group expenses and settle up in the fewest payments possible.

Splitting a trip, a flat, or a dinner ends the same way: a group chat full of "who owes who" and a spreadsheet nobody trusts. Splibilo replaces that: log an expense (or snap the receipt), and it tracks every balance and tells each person the shortest set of payments that clears the group.

Full-stack: NestJS + Next.js (App Router) + PostgreSQL/Prisma.

Quick Start

git clone https://github.com/andeluw/splibilo && cd splibilo

# Backend (NestJS, :8000)
cd backend
cp .env.example .env          # set DATABASE_URL + GEMINI_API_KEY
pnpm install
pnpm prisma migrate dev
pnpm db:seed                  # demo group + expenses
pnpm start:dev

# Frontend (Next.js, :3000) in a new terminal
cd frontend
cp .env.example .env
pnpm install
pnpm dev

Open http://localhost:3000. Requires PostgreSQL and Node 18+.

Features

• Settle in the fewest payments: greedy debt-simplification (O(n log n)) turns a tangle of IOUs into a minimal "who pays whom" list.
• Snap a receipt, skip the typing: Sharp → Tesseract → Gemini pipeline extracts items, tax and total into a prefilled expense form.
• Balances that are always right: every expense/settlement recomputes net balances in real time; custom splits are floating-point-safe, updates are transactional.
• Groups with real permissions: invite by email or code, role-based access (Owner/Admin/Member), archive and lock.
• See where the money goes: trends, category breakdown, top payers, personal summary.
• Secure by default: JWT auth with refresh-token rotation, membership-enforced routes, 90%+ backend test coverage.

Screenshots

Your groups: every shared group, your balance in each, filter by category.

Group overview: balances, spend-over-time, category breakdown, top payers.

Add an expense: split equally or per person, attach a receipt, or prefill it from receipt OCR.

Settlements: what has actually been paid back, and record new transfers.

Your activity: your position across every group, trends, recent expenses and settlements.

How It Works

Balance per member:

net = totalPaid - totalOwed + settlementsReceived - settlementsSent

Debt simplification: separate creditors/debtors, sort by balance, greedy two-pointer match. O(n log n), minimal transaction count.

OCR pipeline: Sharp (preprocess) → Tesseract.js (text) → Gemini (structured JSON: items, subtotal, tax, total) → prefilled expense form.

Tech Stack

Frontend: Next.js 15, React 19, Tailwind v4, Shadcn UI, TanStack Query, Zustand, React Hook Form, Recharts

Backend: NestJS 11, Prisma, PostgreSQL, JWT (refresh rotation), Multer + Sharp, Tesseract.js + Gemini, Nodemailer

Purpose

Built to replace spreadsheets and "who owes who" chats with automated, transparent, fair settlement. A full-stack study in transactional data integrity, algorithmic optimization, and an OCR + LLM extraction pipeline.