> ## Documentation Index
> Fetch the complete documentation index at: https://developers.circle.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Grant USDC allowance to Permit2

> Use Uniswap's Permit2 contract to grant USDC allowance to the StableFX FxEscrow contract

This guide shows an example of how to grant a USDC token allowance to the
`Permit2` contract using a Circle Wallets developer-controlled wallet. The
[`Permit2` documentation](https://docs.uniswap.org/contracts/permit2/overview)
provides additional examples of how to grant this allowance.

When using the [StableFX API](/stablefx/concepts/technical-guide) to deliver the
funds onchain for an FX trade, you must grant an allowance to the
[`Permit2` contract](https://docs.arc.io/arc/references/contract-addresses#permit2)
for the token you are funding. This allows the `Permit2` contract to transfer
the token from your wallet to the `FxEscrow` contract.

## Prerequisites

Before you begin, ensure you have:

* A [Circle Developer Console](https://console.circle.com/) account.

* A
  [developer-controlled wallet](/wallets/dev-controlled/create-your-first-wallet)

* [Node.js 18+](https://nodejs.org/) installed.

* A project set up as described in the below section

### Set up your project

1. Initialize a new Node.js project and install dependencies:

   ```shell theme={null}
   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:

   ```shell theme={null}
   USDC_CONTRACT_ADDRESS=<USDC_CONTRACT_ADDRESS>
   PERMIT2_CONTRACT_ADDRESS=<PERMIT2_CONTRACT_ADDRESS>
   APPROVAL_AMOUNT=<APPROVAL_AMOUNT>
   WALLET_ADDRESS=<WALLET_ADDRESS>
   ```

   The `PERMIT2_CONTRACT_ADDRESS` is the same across all EVM blockchains
   (`0x000000000022D473030F116dDEE9F6B43aC78BA3`), but you should verify it with
   the blockchain explorer on the chain you are using. You can find the
   `USDC_CONTRACT_ADDRESS` on the
   [USDC contract address page](/stablecoins/usdc-contract-addresses).

   <Note>
     The USDC token has 6 decimals. To approve \$100 USDC, set `APPROVAL_AMOUNT` to
     `100000000` (100 \* 10<sup>6</sup>).
   </Note>

   If you are following the Circle Wallets example, you will also need to add
   the following variables:

   ```shell theme={null}
   CIRCLE_WALLET_ID=<CIRCLE_WALLET_ID>
   CIRCLE_WALLETS_API_KEY=<CIRCLE_WALLETS_API_KEY>
   ENTITY_SECRET=<ENTITY_SECRET>
   ```

   If you are not funding USDC, you need to grant allowance using the contract
   address of the token you are funding.

3. Create an `index.js` file. You'll add code step by step in the following
   sections.

### Grant a USDC token allowance to the `Permit2` contract

Add the following code to your `index.js` file to grant a USDC token allowance
to the `Permit2` contract using a Circle Wallets developer-controlled wallet on
supported EVM blockchains.

```javascript theme={null}
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);

---------------------------------- */
```