Splitzz - Expense Splitting Made Easy

A modern expense splitting application built with Next.js, Convex, and Clerk authentication. Split bills with friends, track group expenses, and settle up easily.

Features

• Secure Authentication - Powered by Clerk (Google OAuth, Email/Password)
• 1-on-1 & Group Expenses - Split bills with individuals or groups
• Flexible Splitting - Equal, percentage, or exact amount splits
• Dashboard - View your balances and spending at a glance
• Settlements - Record payments and track who owes what
• User Search - Find and add friends easily
• Email Notifications - Powered by Resend and Inngest
• Responsive Design - Works on desktop and mobile
• Modern UI - Built with Tailwind CSS and ShadCN UI

Tech Stack

• Frontend: Next.js 15 , React 19
• Backend: Convex (Real-time database and serverless functions)
• Authentication: Clerk
• Styling: Tailwind CSS v4
• UI Components: ShadCN UI
• Background Jobs: Inngest
• Email: Resend
• Charts: Recharts
• Icons: Lucide React

Getting Started

Setup

1. Clone and install:

git clone https://github.com/Vedant-0102/Splitz.git
cd splitz
npm install

2. Set up Convex:

npx convex dev

3. Configure environment variables:

Create .env.local:

# Convex (auto-generated by `npx convex dev`)
CONVEX_DEPLOYMENT=dev:your-deployment
NEXT_PUBLIC_CONVEX_URL=https://your-deployment.convex.cloud

# Clerk
NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY=pk_test_your_key
CLERK_SECRET_KEY=sk_test_your_key
NEXT_PUBLIC_CLERK_SIGN_IN_URL=/sign-in
NEXT_PUBLIC_CLERK_SIGN_UP_URL=/sign-up
CLERK_JWT_ISSUER_DOMAIN=https://your-domain.clerk.accounts.dev

# Resend (for email notifications)
RESEND_API_KEY=re_your_key

# Gemini API 
GEMINI_API_KEY=your_gemini_key

4. Run development server:

npm run dev

Project Structure

splitz/
├── app/
│   ├── (auth)/           # Authentication pages
│   ├── (main)/           # Main application
│   │   ├── contacts/     # Contacts & groups
│   │   ├── dashboard/    # Dashboard
│   │   ├── expenses/     # Expense management
│   │   ├── groups/       # Group details
│   │   ├── person/       # 1-on-1 expenses
│   │   └── settlements/  # Settlements
│   └── api/              # API routes
├── components/           # React components
│   └── ui/               # UI components
├── convex/               # Backend functions
│   ├── users.js
│   ├── expenses.js
│   ├── groups.js
│   ├── settlements.js
│   ├── dashboard.js
│   └── schema.js
├── hooks/                # Custom hooks
├── lib/                  # Utilities
│   └── inngest/          # Background jobs
└── public/               # Static files

API Endpoints

Users

• users.current() - Get current authenticated user
• users.store(userData) - Store/update user from Clerk
• users.search(query) - Search users by name or email
• users.all() - Get all users

Expenses

• expenses.create(expenseData) - Create new expense
• expenses.betweenUsers(userId) - Get expenses between two users
• expenses.delete(expenseId) - Delete expense

Groups

• groups.get(groupId) - Get group details
• groups.expenses(groupId) - Get group expenses
• groups.create(groupData) - Create new group

Settlements

• settlements.create(settlementData) - Record payment
• settlements.data(entityType, entityId) - Get settlement history

Dashboard

• dashboard.balances() - Get user balances
• dashboard.totalSpent() - Get total spent
• dashboard.monthlySpending() - Get monthly spending data
• dashboard.groups() - Get user's groups

Contacts

• contacts.all() - Get all contacts
• contacts.createGroup(groupData) - Create contact group

Key Features Explained

Balance Calculation

The app tracks:

• What you owe to others (negative balance)
• What others owe you (positive balance)
• Net balance per person and group

Settlements

Record when someone pays you back:

1. Go to person/group page
2. Click "Settle up"
3. Enter amount and note
4. Submit - balances update automatically

Groups

Create groups for:

• Trips and vacations
• Roommate expenses
• Events and parties
• Regular shared expenses

Development

Building for Production

npm run dev

Deploying

Convex:

npx convex deploy