Splitcast

PROJECT NAME: SplitCast

DESCRIPTION OF THE PROJECT: web app or mini app on farcaster for bill-splitting operation between small group of frinds, it's usefull to remind you your bill and pay them with crypto.

REPOSITORY WITH THE PROJECT'S CODE: https://github.com/Luceva2002/eththon

VIDEO DEMO:

Website URLs of your deployed application: https://eththon.vercel.app/

The contract address(es) you deployed and the chain(s) where you deployed it: Arbitrum Sepolia 0x189a3d17cfed4a076cdc3591373d0fa924b6dd22

Bounties:

BASE | 

How we use Base

We use Base blockchain for wallet login and user onboarding.

What it does

• Easy login: Connect with MetaMask, Coinbase Wallet, or WalletConnect
• Fast & cheap: Base offers quick transactions with low fees
• Simple setup: Uses Wagmi and OnchainKit to manage wallet connections

Why Base

Base is set as the default network (in wagmi-config.ts), making it super easy for Coinbase users to get started without switching networks.

1INCH | 

We integrated 1inch DEX Aggregator so you can pay debts with any crypto token. The system automatically swaps tokens for you.

What it does

Gets prices: Checks real-time rates for token swaps (in api/1inch/quote/route.ts)
Makes swaps: Finds the best swap deals across multiple exchanges (in api/1inch/swap/route.ts)
Manages approvals: Handles token permissions (in api/1inch/approve/route.ts)
Checks allowances: Verifies you've approved the tokens (in api/1inch/allowance/route.ts)

How payments work

The OneInchService handles everything automatically:
Converts your EUR amount to crypto using CoinGecko prices
Gets the best swap rate from 1inchApproves the tokens
Swaps your tokens
Sends the payment to your friend

The result

You can pay with any token you have (ETH, USDC, WETH, ARB, etc.), and your friend receives their preferred token. It all happens through the CryptoPaymentDialog with just a few clicks.

FINANCE | 

SplitCast helps you split bills with friends using cryptocurrency. It's like Splitwise, but for crypto.

Main features

• Multiple currencies: Track expenses in EUR, USD, or crypto
• Auto-calculates debts: Automatically updates who owes what in real-time
• Pay with crypto: Settle debts on the blockchain with full transparency
• Many payment options: Choose from 10+ tokens (USDC, USDT, DAI, WETH, ARB, WBTC, LINK, UNI)
• Live prices: Converts between EUR/USD and crypto using CoinGecko
• Saves on fees: Smart system to minimize gas costs

How it works

The app (in group-service.ts) handles all the math - splitting expenses, tracking payments, and calculating balances. Everything is saved in Supabase so your data is always safe.

ARBITRUM | 

We chose Arbitrum One to handle all crypto payments and 1inch swaps for these reasons:

• Low fees: Much cheaper than Ethereum for swaps
• High liquidity: 1inch works great on Arbitrum with competitive prices
• Fast: Transactions confirm quickly
• Many tokens: Supports a wide range of ERC20 tokens

How it works

All token swaps and transfers happen on Arbitrum (see token-list.ts). We only use verified token addresses from the official Arbitrum bridge.

The payment system (in crypto-payment-dialog.tsx) automatically handles:

• Switching to the Arbitrum network
• Multi-step transactions (approve → swap → transfer)
  • Error handling for Arbitrum-specific issues

Additional Technical Highlights | 

Tech Stack: Next.js 15 (App Router), 
TypeScript, 
Tailwind CSS, 
shadcn/ui, 
Wagmi, 
Viem,
Authentication: Supabase for user management and persistent storage
Wallet Integration: MetaMask, Coinbase Wallet, Phantom
Responsive Design: Mobile-first UI with dark mode support