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For Transactions V2 on EVM blockchains, there is a dependency on the Permit2 contract to enable allowance management. To get the benefits of Transactions V2, you must grant a USDC token allowance to the Permit2 contract. This guide shows two examples of how to grant a USDC token allowance to the Permit2 contract. The Permit2 documentation provides additional examples of how to grant this allowance.

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Prerequisites

The examples on this page show how to grant a USDC token allowance to the Permit2 contract using a Circle Wallets developer-controlled wallet or a generic EIP-1193 Ethereum wallet. Before you begin, ensure you have:
  • If you are following the Circle Wallets example:
  • Node.js and npm installed on your development machine
  • A project set up as described in the below section

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Set up your project

  1. Initialize a new Node.js project and install dependencies: 
    npm init -y
npm pkg set type=module
npm install viem dotenv
  2. In the project root, create a .env file and add the following variables: 
    USDC_CONTRACT_ADDRESS=<USDC_CONTRACT_ADDRESS>
PERMIT2_CONTRACT_ADDRESS=<PERMIT2_CONTRACT_ADDRESS>
APPROVAL_AMOUNT=<APPROVAL_AMOUNT>
WALLET_ADDRESS=<WALLET_ADDRESS>
    Note: The USDC token has 6 decimals. To approve $100 USDC, set APPROVAL_AMOUNT to 100000000 (100 × 10^6).
    If you are following the Circle Wallets example, you will also need to add the following variables: 
    CIRCLE_WALLET_ID=<CIRCLE_WALLET_ID>
CIRCLE_WALLETS_API_KEY=<CIRCLE_WALLETS_API_KEY>
ENTITY_SECRET=<ENTITY_SECRET>
    If you are following the EIP-1193 Ethereum wallet example, or your Circle Wallet is on the generic EVM / EVM-TESTNET chain, you will also need to add the following variable: 
    RPC_URL=<RPC_URL>
  3. Create an index.js file. You’ll add code step by step in the following sections.

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Steps

The following steps show how to grant a USDC token allowance to the Permit2 contract using a Circle Wallets developer-controlled wallet or an EIP-1193 Ethereum wallet.

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Step 1. Grant a USDC token allowance to the Permit2 contract

The following example code shows the process for granting a USDC token allowance to the Permit2 contract using a Circle Wallets developer-controlled wallet or an EIP-1193 Ethereum wallet.
  • Circle Wallets
  • Circle Wallets (generic EVM)
  • EIP-1193 Ethereum Wallet
Note: This example is for a Circle Wallets developer-controlled wallet on specific EVM blockchains (e.g. ETH, ETH-SEPOLIA, MATIC, MATIC-AMOY, etc.). If your Circle Wallet is on the generic EVM / EVM-TESTNET chain, which is likely the case if you are migrating from Transactions V1 to V2, you can use the example in the “Circle Wallets (generic EVM)” tab. 
import { initiateDeveloperControlledWalletsClient } from "@circle-fin/developer-controlled-wallets";
import { randomUUID } from "crypto";
import dotenv from "dotenv";

dotenv.config();

/**
 * Approves a specified amount of USDC for the Permit2 contract using
 * a developer-controlled wallet managed by Circle.
 *
 * This function sends an on-chain transaction to call the ERC-20 `approve`
 * method on the USDC contract, allowing the Permit2 contract to spend
 * the specified amount on behalf of the wallet.
 *
 * @async
 * @function approveUSDCWithCircleWallets
 * @returns {Promise<object>} The transaction response data returned by Circle's API.
 */
export async function approveUSDCWithCircleWallets() {
  const client = initiateDeveloperControlledWalletsClient({
    apiKey: process.env.CIRCLE_WALLETS_API_KEY,
    entitySecret: process.env.ENTITY_SECRET,
  });

  const response = await client.createContractExecutionTransaction({
    walletId: process.env.CIRCLE_WALLET_ID,
    contractAddress: process.env.USDC_CONTRACT_ADDRESS,
    abiFunctionSignature: "approve(address,uint256)",
    abiParameters: [
      process.env.PERMIT2_CONTRACT_ADDRESS,
      process.env.APPROVAL_AMOUNT,
    ],
    idempotencyKey: randomUUID(),
    fee: { type: "level", config: { feeLevel: "MEDIUM" } },
  });

  return response.data;
}

/* -------- Example usage with Circle ---------

// For auth and wallet creation, see: https://developers.circle.com/interactive-quickstarts/dev-controlled-wallets
const response = await approveUSDCWithCircleWallets();
console.log('Response:', response);

---------------------------------- */