Polygon Is Now Live on RelAI - Gas-Free x402 Payments on the Fastest EVM Chain

We're excited to announce that Polygon (eip155:137) is now fully supported on the RelAI Facilitator - bringing gas-free, one-signature USDC payments to one of the most widely adopted EVM networks.

Why Polygon?

Polygon is the go-to L2 for cost-effective, high-throughput transactions. With over 3 million daily active addresses and sub-second finality, it's the natural choice for API monetization at scale. But even on Polygon, gas fees add friction - especially for microtransactions like API calls.

That's where RelAI comes in.

How It Works

RelAI eliminates gas fees entirely for the end user. Here's the flow:

1. User requests a protected API - a standard GET/POST to your x402-enabled endpoint
2. Backend returns HTTP 402 - with x402 v2 payment requirements including the RelAI feePayer address
3. User signs an EIP-3009 transferWithAuthorization - a single off-chain signature, no gas needed
4. RelAI settles the payment - our backend wallet submits the transaction and pays POL for gas
5. User gets the API response - seamless, instant access

Technical Details

Why EIP-3009 Instead of EIP-2612?

We use EIP-3009 transferWithAuthorization across all EVM networks - not EIP-2612 permit. Here's why:

• Single transaction - transferWithAuthorization moves tokens in one call, while permit requires a separate transferFrom afterward
• Better nonce model - EIP-3009 uses random bytes32 nonces, eliminating nonce ordering issues
• Built for delegated transfers - the standard was designed specifically for this use case
• Native USDC support - Circle's USDC contract natively supports EIP-3009 on all major chains

For Developers

Setting Up Polygon Payments

If you're already using RelAI on other networks, Polygon works out of the box. Just set your API's network to polygon:

// Your API pricing configuration
{
  network: 'polygon',
  facilitator: 'relai',
  pricing: {
    'GET /data': { amount: '10000' }  // $0.01 in USDC (6 decimals)
  }
}

Using the RelAI SDK

import { createRelaiClient } from '@relai-fi/x402'
const client = createRelaiClient({
  evmWallet: {
    address: userAddress,
    signTypedData: wallet.signTypedData,
  }
})
const response = await client.fetch('https://your-api.com/data')
// Payment handled automatically  - user signs once, RelAI pays gas

RPC Configuration

We use polygon-bor-rpc.publicnode.com as our default Polygon RPC - chosen for reliability and lack of batch size limits that plague some public endpoints.

What This Means for Users

• Zero gas fees - RelAI pays POL for every transaction
• One signature - no approve + transfer, just a single typed data signature
• Instant access - payment settles in ~2 seconds on Polygon
• Works with any wallet - MetaMask, Phantom, WalletConnect, or custodial RelAI wallets

What's Next

Polygon joins Ethereum, Base, Avalanche, SKALE, and Solana in the RelAI network. We're continuing to expand support to bring gas-free x402 payments to every major chain.

Start building with Polygon on RelAI today at relai.fi.