The Problem

Splitting expenses with friends shouldn’t require a spreadsheet. But existing tools fall short:

Splitwise handles basic splits but can’t scan receipts, settle poker games, or automate reminders based on debt age
Venmo/PayPal track payments but not who owes what across multiple expenses
Group chats turn into “did you pay me?” arguments with no resolution

We needed something that handles the full range, from a restaurant bill split four ways to a weekly poker game with rebuys to recurring rent with roommates.

The Solution

FairSlice is a full-stack expense-splitting platform with AI-powered intelligence.

Expense Splitting: 4 Methods

Equal: Auto-rounding so no one gets shorted by a penny
Unequal: Exact amounts when someone had the expensive dish
Percentage: Split by ownership stake or agreed ratios
Shares: Weighted splits (2 shares vs 1 share)

Plus: multi-payer support (Alice paid $60, Bob paid $40 for the same expense), itemized restaurant splitting, and expense templates for recurring setups.

AI Receipt Scanning

Snap a photo of any receipt and Claude Vision extracts:

Merchant name, item list with quantities and prices
Tax, tip, and total with currency detection
Confidence scoring for accuracy

Then assign items to people. Tax and tip split proportionally. No manual entry needed.

Smart Categorization

Two-tier system: keyword matching across 16 categories (food, transport, housing, etc.) handles most expenses instantly. For ambiguous descriptions, Claude Sonnet classifies them with high accuracy.

Game Session Settlements

Built-in support for poker nights, rummy, teen patti, and more:

8 game templates: Texas Hold’em, Rummy, Teen Patti, Spades, Blackjack, Baccarat, Mahjong, 21
Buy-in + rebuy tracking per player
Two scoring modes: chip-based (poker) and point-based (rummy/mahjong)
One-tap settlement: calculates optimized transfers automatically

Debt Simplification

If Alice owes Bob $20, Bob owes Charlie $15, and Charlie owes Alice $10, FairSlice reduces that to the minimum number of transfers. Never more than N-1 transfers for N people. Uses a greedy matching algorithm pairing largest debtor to largest creditor.

Smart Reminders

Automatic reminders based on debt aging:

Fresh debts (< 7 days): no reminders
Normal (7–30 days): remind if amount >= $50
Aging (30–90 days): remind every 14 days
Stale (90–180 days): remind every 7 days
Ancient (> 180 days): remind every 3 days

Financial Insights

Fairness Score: Gini coefficient measuring how evenly expenses are distributed (0–100)
Category breakdown: Spending by category per person
Balance trends: Historical snapshots to track debt aging
Urgency scoring: Flags important debts by combining amount and age

More Features

Multi-currency: 150+ currencies with real-time conversion
Settlement confirmation: Payments require receiver confirmation, eliminating disputes
10 payment methods: Cash, Venmo, PayPal, Zelle, UPI, Apple Pay, Google Pay, Interac, Revolut, Wise, crypto
Friend system: 1:1 expense tracking outside of groups
Recurring expenses: Auto-create weekly/monthly expenses via cron
CSV import/export: Bulk migration and GDPR-compliant data export
Webhooks: Subscribe to 9 event types with HMAC signing and auto-retry
Global search: Cmd+K search across expenses, groups, and friends

Tech Stack

Next.js 16: App Router with 107 API routes
TypeScript: Strict mode, 250+ type definitions
React 19 with Tailwind CSS v4
Supabase: PostgreSQL, Auth, Realtime channels for instant updates
Anthropic Claude: Vision for receipt scanning, Sonnet for categorization
Vercel: Edge deployment with daily cron jobs
Zod 4: Runtime validation across all API inputs
Vitest: Testing framework

Security

Rate limiting across 4 tiers (standard, heavy for AI ops, auth, export)
CSRF protection with Origin header validation
Webhook delivery with SSRF protection, HMAC-SHA256 signing, and exponential backoff retries
Privacy controls for email/phone visibility
Full account deletion support

FairSlice — Expense Splitting for Groups and Game Nights