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Fintech ~10 hours to build

Smart Expense Splitter

Group expenses without the awkward conversations.

The Problem

Every group trip, every dinner with friends, every shared house ends the same way: someone Venmo-requesting, others forgetting who paid what, and awkward "you still owe me $23" conversations weeks later. Splitwise exists but feels dated and bloated. People want something simpler.

The Solution

A clean, modern expense splitter that creates a group, logs expenses, and calculates the minimum number of payments needed to settle up. Integrates with Venmo/PayPal for one-tap settlement. Works great for trips, roommates, and regular dinner groups.

How it works:

1

Create group

Invite friends via link

2

Log expenses

Who paid, who's involved

3

Settle up

Optimized payments via Venmo

Market Research

Group expense tracking is an evergreen category with one dominant incumbent and a long tail of me-toos. The opportunity is not inventing a new category—it is modern UX, faster settlement, and niche modes (group travel, roommates, couples) that the incumbent has underserved for nearly a decade.

  • Splitwise reports 50M+ downloads and last raised on a $1B+ valuation; Pro tier at $4/mo is the market's price anchor.
  • Global outbound tourism has fully recovered past 2019 levels (UNWTO 2024)—group trips are the highest-intent use case for a splitter.
  • Zelle processed $1T+ in P2P payments in 2023 and Venmo passed $270B in annual TPV—settlement rails are solved; splitting UX is not.
  • Gen Z and Millennials split 3+ recurring expenses with housemates on average (Zillow / Pew housing surveys); roommate is a sticky, monthly use case.

Competitive Landscape

Splitwise owns the brand; Venmo owns the default. Everyone else fights for niche use cases. Your opening is modern UX plus a specific mode the incumbent neglects—group travel receipt parsing, multi-currency, or a roommate-first recurring bills layout.

Splitwise

Category king. Works, but UI is a decade old, Pro tier feels nickel-and-dimed, and the travel-specific workflow (multi-currency, receipt photos, exchange rates) still requires workarounds.

Free with ads → $4/mo Pro (no ads, receipts, currency conversion)

Tricount

Euro-popular, travel-first. Slick enough on the app, but no dominant US presence and the web experience is weak—opening for a travel splitter with a tight trip-pass offer.

Free with ads → €2.99/mo Premium

Settle Up

Clean, minimal, indie. Good multi-currency handling but weaker viral loops—nobody talks about Settle Up the way they talk about Splitwise. Product is fine; distribution is the gap.

Free → $2.99/mo or $14.99/yr Premium

Venmo / Cash App

The “just Venmo me” default. Kills intent once per transaction but has no group math, no history per trip, no recurring bill logic. Co-existence play: export settled balances as a Venmo / Cash App request link.

Free for P2P; no splitting or group tracking UX

Your Opportunity

Ship a modern, mobile-first PWA that nails one niche hard—group travel with OCR receipt capture and live multi-currency, or a roommate-first recurring bills home—then widen. Splitwise’s stagnation and Venmo’s non-answer are both the opening.

Business Model

Freemium subscription priced at the category floor, plus a one-time Trip Pass that captures the high-intent travel moment without asking tourists to start a monthly subscription. Free tier seeds viral group invites; Pro monetizes housemates and repeat trip organizers.

Free

$0

1 active group, up to 5 members, basic split math, Venmo/Cash App hand-off

Pro

$3.99/mo

Unlimited groups, recurring expenses, multi-currency, receipt OCR, CSV export

Trip Pass

$9.99 once

One trip, unlimited members, full feature set for 30 days—no subscription

Unit Economics (illustrative)

Target CAC

$2–6

Viral k-factor

1.8–2.4

Pro conversion

3–5%

Trip Pass attach

8–12%

Recommended Tech Stack

PWA-first is the call—travelers on patchy hotel Wi-Fi need offline expense entry that syncs later. Next.js covers marketing + app + API in one deploy; Supabase handles auth, Postgres, and Realtime for live group balance updates; OCR via GPT-4o Vision keeps receipt capture a single API call.

Next.js 14 PWA + TypeScript

App Router, installable PWA with service worker for offline expense entry. IndexedDB queue drains to Postgres on reconnect.

Supabase

Auth + Postgres for groups/members/expenses, Realtime for live balance updates, Storage for receipt images, RLS per group membership.

GPT-4o Vision (receipts)

Single API call parses receipt photo into merchant, total, line items, and currency. Gate behind Pro + Trip Pass to keep margin positive.

Stripe

Checkout + Billing Portal for Pro subscriptions; one-off Payment Links for Trip Pass. Webhook-driven entitlement sync.

Open Exchange Rates

Daily FX rates for multi-currency trips; store rate-at-entry on the expense so historical balances don’t drift.

Resend

Trip summary emails, recurring-bill reminders, “you owe / you’re owed” nudges with one-click settle links.

AI Prompts to Build This

Copy and paste these into Claude, Cursor, or your favorite AI tool.

1. Project Setup

Create a Next.js PWA for an Expense Splitter app. Features: - Landing page with "Start a Group" CTA - Create group: name, invite link generation - Group dashboard: members, expenses list, balance summary - Add expense modal: amount, description, who paid, split type (equal/exact/percentage) - Each member sees their balance (owed/owing) Use Supabase auth (magic link for easy onboarding) and database. Make it installable as PWA for mobile.

2. Core Feature

Implement the settlement optimization algorithm: 1. Calculate net balance for each person (total paid - total owed) 2. People with positive balance are owed money; negative balance owe money 3. Implement minimum transaction algorithm: - Sort creditors and debtors - Match largest debtor with largest creditor - Settle minimum of both amounts - Repeat until all settled 4. Display settlement plan: "Alice pays Bob $50" etc. This minimizes total number of transactions needed.

3. Payment Integration

Add payment links for settlement: - Generate Venmo deep links: venmo://paycharge?txn=pay&recipients={username}&amount={amount}¬e={description} - Generate PayPal.me links: paypal.me/{username}/{amount} - Add "Mark as Paid" button to manually record settlements - Send push notification when someone marks payment complete - Keep history of all settlements Allow users to save their Venmo/PayPal username in settings.

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