Arc Stablecoin FX

This sample app demonstrates stablecoin FX swaps between USDC and EURC using the App Kits Swap SDK and Circle Developer Controlled Wallets on Arc.

Getting started

Prerequisites

• Node.js 20+ and npm
• Docker (for local Supabase)
• A Circle account with API key + entity secret
• A Circle App Kit KIT_KEY

1. Install dependencies

npm install

2. Start the local Supabase stack

npm run db:start

This boots Postgres, Auth, etc. via the Supabase CLI and runs the migrations in supabase/migrations/. Use npm run db:status to print the local URLs and keys, npm run db:reset to wipe + re-migrate, and npm run db:stop to shut it down.

3. Configure environment

Copy the example file and fill in the blanks:

cp .env.example .env.local

• NEXT_PUBLIC_SUPABASE_URL / NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY / SUPABASE_SECRET_KEY - from npm run db:status.
• CIRCLE_API_KEY - from the Circle console.
• CIRCLE_ENTITY_SECRET - your 32-byte hex entity secret. Must be registered with Circle once before use.
• CIRCLE_BLOCKCHAIN - Circle blockchain identifier (default ARC-TESTNET).
• KIT_KEY - Circle App Kit key.
• NEXT_PUBLIC_ARC_CHAIN - App Kit chain identifier (default Arc_Testnet).
• APP_FEE_BPS - platform fee in basis points (default 25 = 0.25%).
• APP_FEE_RECIPIENT - leave blank, then run the script below.

4. Provision the platform fee wallet

Creates a Circle wallet to receive swap fees and writes its address back to .env.local as APP_FEE_RECIPIENT:

npm run wallet:generate

5. Run the dev server

npm run dev

App is running at http://localhost:3000.

Project layout

• src/app/(auth)/ - register / login flows
• src/app/(app)/dashboard/ - authenticated swap panel
• src/app/(app)/dashboard/history/ - trades history
• src/app/api/webhooks/circle/ - Circle webhook receiver
• src/components/swap/, src/components/trades/, src/components/wallet/ - feature UI
• src/lib/circle/, src/lib/appkit/ - Circle wallets + App Kit integration
• src/lib/supabase/ - Supabase client/server/admin helpers
• supabase/migrations/ - database schema
• scripts/ - one-off operator scripts

Legal

Sample apps provided for demonstration and educational purposes only, intended for Arc testnet use only, and not production-ready. See Arc.io for more.