X402 Payment

X402 is a decentralized payment protocol that lets your app accept crypto payments with gasless transactions — users only pay the token amount (like USDC), no native gas fees required.

Noah can set up X402 payment integration for you. Just describe what you need in chat.

X402 supports both EVM chains (Base, Polygon, Avalanche, Sei) and Solana. Choose the right setup based on your target chain.

Key Features

• Gasless Transactions — No ETH, MATIC, SOL, or any native token needed for gas fees
• Token Payments Only — Users pay the exact amount in USDC (or other supported tokens)
• Multi-Network — Base, Polygon, Avalanche, Sei, Solana, and more
• Real-Time Processing — Instant payment verification and confirmation

Requirements

Before integrating X402 with your Noah app:

• Your app has a connected wallet flow (EVM or Solana)
• You have a receiving wallet address to accept payments
• Your project can be deployed (X402 works best on deployed URLs)

Setting Up X402 for EVM Chains

Noah can set up X402 payment for EVM chains. Just describe what you need and Noah will generate the payment service, UI components, and wallet connection logic.

Supported EVM Networks

Network	ID
Base	base
Base Sepolia (Testnet)	base-sepolia
Polygon	polygon
Polygon Amoy (Testnet)	polygon-amoy
Avalanche	avalanche
Avalanche Fuji (Testnet)	avalanche-fuji
Sei	sei
Sei Testnet	sei-testnet
IoTeX	iotex
Peaq	peaq

Example Prompts for EVM

Quick payment button:

Add a "Pay $1" button that uses X402 payment on Base network. When clicked, it should process a USDC payment using the connected wallet and show a success message.

Subscription-style payment:

Create a pricing page with Starter ($5) and Pro ($15) plans. Use X402 on Polygon to process payments. After payment, update the user's plan in the database.

Custom payment amount:

Add a payment form where users can enter a custom amount. Process the payment through X402 on Base Sepolia for testing. Show the transaction details after success.

Setting Up X402 for Solana

For Solana payments, Noah handles the setup using the x402-solana package.

Supported Solana Networks

Network	ID	Token
Solana Mainnet	solana	USDC
Solana Devnet	solana-devnet	USDC-devnet

Token is auto-selected based on network — devnet uses USDC-devnet, mainnet uses USDC. No manual token configuration needed.

Example Prompts for Solana

Simple Solana payment:

Add a payment button that charges 0.1 USDC on Solana using X402. Use the connected Solana wallet to sign the transaction. Show success with the transaction hash.

Solana devnet testing:

Set up X402 payment on Solana devnet for testing. Add a test payment flow where I can enter an amount and process USDC-devnet payments. Show transaction details on success.

Securely Store Your Wallet Address

1. Get your receiving wallet

   Use any wallet address where you want to receive payments.

   • For EVM: Your Ethereum-compatible wallet address (0x…)
   • For Solana: Your Solana wallet address
2. Store it in Noah

   In your Noah project, open Settings and add your wallet address as an environment variable:

   • EVM: VITE_REACT_APP_X402_RECEIVING_WALLET
   • Solana: VITE_REACT_APP_X402_RECEIVING_WALLET_SOLANA

   Never paste wallet private keys into chat or code. Only store the public receiving address as an environment variable.

Testing

• Start with testnet networks (Base Sepolia, Solana Devnet) before going live
• X402 handles gas fees — users only need USDC balance
• Test both successful and failed payment flows
• Deploy your app to test end-to-end (redirects, confirmations)

Troubleshooting

Payment fails with insufficient funds

The user doesn’t have enough USDC (or the test token) in their wallet. X402 only needs the token balance — no native gas token required.

Wallet not connected

Make sure your app has a wallet connection flow set up before triggering payments. Ask Noah to add wallet connect if you don’t have it yet.

Wrong network

Ensure the user’s wallet is on the same network as the payment config. Ask Noah to add network switching if needed.

Ask Noah for help

Switch to Plan mode and describe what’s failing. Noah can review your X402 setup and suggest fixes.