ChainSplit

Decentralized expense splitting on Cronos. No middlemen. No trust issues. Just code.

chain-split.vercel.app  ·  GitHub  ·  Setup

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You've split bills on Splitwise. You've chased friends for money on Venmo. You've trusted some company's database to keep track of who owes what.

ChainSplit puts all of that on-chain. Each group deploys its own smart contract vault on Cronos EVM. Members log expenses, the contract calculates settlements using a greedy debt-minimization algorithm, and everyone settles peer-to-peer — no platform in the middle, no accounts, no trust required.

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Deployments

Service	URL
Frontend	chain-split.vercel.app
Backend API	chainsplit-389w.onrender.com
Database	MongoDB Atlas
File Storage	Pinata (IPFS)

Factory Contract — Cronos Testnet (338)

0xe9256300bb409b5Cf8CF16aDD6A0aDB0cc72E5bf

Get testnet CRO → cronos.org/faucet

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How it works

1.  A group admin calls createGroup()
    → Factory deploys a fresh GroupVault contract

2.  Admin invites members via addMember(address, name)

3.  Members deposit CRO into the vault

4.  Anyone logs an expense:
    addExpenseEqual()   →  split evenly across members
    addExpenseCustom()  →  assign custom weights per person

5.  calculateSettlements() runs a greedy algorithm
    → returns the minimum set of transactions to clear all debts

6.  Each debtor calls settleDebt(creditor)
    → CRO transfers directly, 1% protocol fee applied

7.  Admin calls markGroupSettled() to close the vault

No off-chain matching. No central server holding funds. The contract is the arbiter.

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Contracts

ChainSplitFactory.sol

Entry point. Deploys a GroupVault per group and maintains a global registry.

function createGroup(
    string memory _name,
    string memory _emoji,
    string memory _adminName
) external returns (address vault);

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GroupVault.sol

One contract per group. Owns all logic — membership, expenses, net balance computation, fund flows.

addMember(address, name)       // Admin: add a wallet to the group
deposit()                      // Member: deposit CRO into vault
addExpenseEqual(...)           // Member: log an equal-split expense
addExpenseCustom(...)          // Member: log a weighted expense
calculateSettlements()         // Public: returns optimal settlement paths
settleDebt(address creditor)   // Member: pay a creditor (1% fee)
markGroupSettled()             // Admin: lock the group
withdrawRemaining()            // Admin: reclaim leftover balance

Security

• Custom nonReentrant guard on all ETH-transfer functions
• onlyAdmin / onlyMember / notSettled access modifiers
• No external contract calls — zero attack surface from dependencies

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Stack

Smart Contracts — Solidity 0.8.24, Hardhat, deployed on Cronos EVM

Frontend — Vite + React 18 + TypeScript, TailwindCSS, wagmi v2, RainbowKit, viem

Backend — Express + TypeScript, Mongoose, ethers.js v6, Pinata SDK, express-rate-limit

Infrastructure — Vercel (frontend), Render (backend), MongoDB Atlas, Pinata IPFS

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Project Structure

ChainSplit/
├── contracts/
│   ├── ChainSplitFactory.sol
│   └── GroupVault.sol
│
├── frontend/
│   └── src/
│       ├── pages/          # Dashboard, Groups, Activity, Profile
│       ├── hooks/          # Custom wagmi hooks
│       ├── abis/           # Contract ABIs + addresses
│       └── config/         # wagmi / RainbowKit config
│
└── backend/
    └── src/
        ├── routes/         # /groups, /expenses, /users
        ├── models/         # Mongoose schemas
        └── services/       # Chain indexer, IPFS service

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Getting Started

Prerequisites

• Node.js 18+
• MetaMask (or any Cronos-compatible wallet)
• MongoDB Atlas URI
• Pinata credentials
• WalletConnect v2 Project ID

Install & run

# Clone
git clone https://github.com/0xMayurrr/ChainSplit.git
cd ChainSplit

# Contracts
npm install
npm run compile
cp .env.example .env        # Add PRIVATE_KEY + CRONOS_TESTNET_RPC_URL
npm run deploy:testnet

# Backend
cd backend
cp .env.template .env       # Add MONGODB_URI, PINATA_*, FACTORY_ADDRESS
npm install && npm run dev   # → localhost:3000

# Frontend
cd frontend
cp .env.example .env        # Add VITE_FACTORY_ADDRESS, VITE_WALLETCONNECT_PROJECT_ID
npm install && npm run dev   # → localhost:5173

Environment Variables

Frontend

Key	Description
VITE_FACTORY_ADDRESS	Factory contract on testnet
VITE_FACTORY_ADDRESS_MAINNET	Factory contract on mainnet
VITE_WALLETCONNECT_PROJECT_ID	From cloud.walletconnect.com
VITE_NETWORK	testnet or mainnet
VITE_API_URL	Backend base URL

Backend

Key	Description
MONGODB_URI	MongoDB Atlas connection string
FACTORY_ADDRESS	Testnet factory address
CRONOS_TESTNET_RPC_URL	Cronos testnet RPC
PINATA_API_KEY	Pinata API key
PINATA_JWT	Pinata JWT (recommended)
FRONTEND_URL	CORS allowed origin

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Contributing

git checkout -b feat/your-feature
git commit -m "feat: describe your change"
git push origin feat/your-feature
# open a PR

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License

MIT — see LICENSE

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Built by 0xMayur  ·  Cronos EVM  ·  Solidity