Connect expenses to members
- What
- Groups can record shared expenses.
- Why
- A useful balance needs to account for who paid and who shares the cost.
- How
- The application uses member and expense information to calculate balances.
Tripmate
Group expense management and settlement application with greedy debt resolution.
01 / The Problem & Analysis
Group travelers struggle with complex multi-payer expenses, uneven currency splits, and awkward manual debt reconciliation.
02 / Engineering & BA Role
Full-Stack Software Engineer (Sole Developer)
03 / Outcome
Minimizes total required cash transactions across participants using a greedy debt-simplification algorithm.
Overview
Tripmate helps groups record shared expenses, calculate who owes whom and simplify the final settlement between members using a greedy graph resolution algorithm.
What I built
Implemented a greedy balance resolution graph algorithm in TypeScript, multi-party expense splitting logic, UPI deep links, and PDF summary exports.
Product Interface
tripmate.boats
Live
Engineering Decisions
Explain the settlement
- What
- Members can see who owes whom.
- Why
- A group needs actionable settlement amounts after recording expenses.
- How
- Balance calculations feed the settlement workflow.
Support the next action
- What
- Settlements include UPI links and PDF exports.
- Why
- Members need to make payments and keep a readable expense record.
- How
- The application creates payment links and generates a PDF from the expense information.
Data Architecture & Schema
The application stores groups, members and shared expense information. Expense and member relationships support the balance and settlement calculations.
trip_id- UUID · Unique trip join code partition
creator_id- UUID · Trip organizer user identifier
expense_id- UUID · Itemized transaction record
amount- NUMERIC · Total expenditure value in INR
payer_id- UUID · Paying member identifier
split_type- TEXT · equal / custom / percentage / quantity
settled- BOOLEAN · Pairwise balance settlement flag
category- TEXT · Lodging / Dining / Transit / Activity
API & System Workflow
The interface connects group and expense actions to stored application data. Settlement amounts are used to create UPI payment links; PDF generation makes the expense information exportable.
- Expense
- Participants
- Balance Calculation
- Settlement Algorithm
- UPI / PDF Export
End-to-end system lifecycle
Representative Implementation
Settlement engine · Minimized-debt greedy balance resolution. Excerpt from the repository source.
// Minimized-debt greedy balance resolution algorithm
export function simplifyDebts(balances: Map<string, number>): Settlement[] {
const debtors = [...balances.entries()].filter(([_, b]) => b < -0.01).sort((a,b) => a[1] - b[1]);
const creditors = [...balances.entries()].filter(([_, b]) => b > 0.01).sort((a,b) => b[1] - a[1]);
const settlements: Settlement[] = [];
// Greedy balance resolution cancels circular obligations
return settleGreedy(debtors, creditors, settlements);
}Interface & Features
The group expense interface brings expense entry, member balances and settlement actions together.
- Shared expense splitting
- Balances and settlements
- UPI payment links
- PDF exports
Technology Stack
- Next.js
- React
- TypeScript
Next.js · React · TypeScript · PostgreSQL/data-backed application · Expense calculations · Settlement logic · API integration · PDF generation