Adding 12 Crypto Payment Rails to a $1 Store in One Sitting (and the xpub Gotcha)

This reporter examined the source material to create an account of an incident involving a tiny digital-products store that faced issues with its payment methods. The store had initially been receiving 96 visitors over two days but no orders. After investigation, the reporter discovered that the store had only one payment method enabled - USDC on Solana. This limited the variety of cryptocurrencies that customers could use to pay, resulting in most visitors abandoning their carts at the checkout stage.

The reporter aimed to fix this issue in approximately half an hour. The solution involved adding 12 different crypto payment rails to the store's setup. SellApp crypto gateways, which the store used, are direct to wallet, meaning there is no processor holding funds, no KYC wall, and no middleman cut. The store simply pastes a receiving address (or xpub, which will be explained further) and the payments land directly in the store's wallet.

The setup proved to be quite efficient, covering 12 payment methods. Instead of needing 12 separate wallets, the store could use 4 keys: one for EVM chains (Ethereum, BNB Chain, Polygon, and ERC20/BEP20 tokens), and one for Solana-native assets (SOL, USDT and USDC on SPL).

However, there were two significant gotchas to navigate during this process. The first gotcha was related to Bitcoin and Litecoin, which required an extended public key (xpub) instead of a standard address. The reporter learned this the hard way as entering the bech32 Bitcoin address into the BTC gateway resulted in a silent rejection.

The solution was to generate a proper HD wallet, deriving a fresh address for each order from the xpub. This ensures better privacy, no address reuse, and funds still end up in wallets controlled by the same seed.

The second gotcha involved the realization that one EVM address could be used for all Ethereum, BNB Chain, Polygon, USDT-ERC20, USDC-ERC20, USDT-BEP20, and USDC-BEP20 payments. A similar principle applied to Solana, where a single base58 address could handle SOL, USDT-SPL, and USDC-SPL payments. The store previously thought each token needed a separate infrastructure, which proved to be a misconception.

In conclusion, by addressing these gotchas and adding the 12 crypto payment rails, the store experienced a significant improvement in its checkout process. The store could now accept payments in various cryptocurrencies, eliminating the 'wrong coin' issue that deterred potential customers. This report provides a practical guide to implementing similar changes in a small store facing similar payment issues.