iGaming Crypto Wallet Integration

I need a seasoned blockchain developer to wire a multi-wallet flow into my existing iGaming platform. Players must be able to make deposits, withdraw winnings, and move balances between their own on-site wallets while we quietly sweep funds into our hot and cold vaults for risk management.

Currencies in scope are Bitcoin (BTC), Ethereum (ETH), Litecoin (LTC), and SOL. The front-end is React/Next.js, the back-end exposes REST and GraphQL endpoints, and we already run a PostgreSQL ledger that records every chip and token—your job is to connect on-chain activity to that ledger with real-time confirmations and webhook callbacks.

Key requirements
• End-to-end handling of Deposits, Withdrawals, and Transfers between wallets.
• Automated sweeps batching user balances into predefined hot / cold addresses on configurable thresholds.
• Support for common browser and mobile wallets (e.g., MetaMask, Coinbase Wallet, Trust Wallet) while remaining flexible enough to plug additional providers later.
• Clear, signed messages so users never have to paste addresses by hand.
• Comprehensive unit tests plus a staging script so QA can replay typical casino flows.

Acceptance criteria
1. A user can deposit BTC, ETH, LTC, or SOL and see confirmed credit in under one minute (testnet first, mainnet on go-live).
2. Withdrawals trigger on-chain transactions, update the ledger, and push a success/fail webhook our side.
3. Sweep service moves idle funds hourly, emits audit logs, and never exposes private keys in code.
4. All code delivered via private Git repo with README and environment sample.

If you’ve integrated blockchain payments into finance or gaming apps before, let’s talk timelines and milestones—our launch window is tight.