A production-ready, self-hosted crypto payment gateway that lets any store or platform accept USDT, USDC, ETH, and BNB payments directly into the merchant's own wallet — with zero platform fees and zero third-party custody.

Unlike hosted solutions (NOWPayments, BitPay) that route funds through their own accounts and charge ongoing fees, this gateway derives unique receiving addresses from the merchant's public key (xPub) only. Private keys never touch the server — funds move directly from buyer to merchant on-chain.

Key features:

- Non-custodial address derivation (ethers.js v6, BIP32)

- Multi-network support: Ethereum, BSC, Polygon, Arbitrum, Base

- Automatic blockchain scanning with confirmation tracking

- Encrypted merchant credentials (AES-256-GCM) + secure API authentication

- BullMQ-powered background workers for transaction detection and webhook delivery

- Live checkout page with QR code, real-time status updates via WebSocket

- Built with TypeScript, Express, Prisma, PostgreSQL, and Redis

Fully documented (API reference, installation guide, disclaimer) and tested with real concurrency and integration tests. Deploy in minutes to any Node.js hosting environment.