Self-Hosted Crypto Payments

What This Skill Does

Adds a complete, production-ready crypto payment system to any Next.js 14+ App Router app backed by Supabase. No Stripe, no CryptAPI, no payment processor — you keep 100% of every payment.

Supported chains & coins: ETH, Base, Polygon, Arbitrum, Optimism, BNB Chain, Avalanche, Solana, Bitcoin — including USDC/USDT/DAI stablecoins on each chain.

Architecture:

1. User picks coin → server derives a unique HD wallet address (BIP44/84/SLIP-0010)
2. Server stores address + expected amount in DB with a 1-hour expiry
3. A cron job polls the actual blockchain every minute, verifies balance, confirms payment
4. On confirmation, credits/plan/addon is applied atomically to the user's profile

Security model: Mnemonic never touches client or source code. User cannot influence destination address or amount. Payment confirmation is blockchain-verified, not webhook-forgeable.

Files to Copy