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Deposit tokens to Arbitrum

This guide shows you how to deposit ERC-20 tokens from a parent chain (like Ethereum) to an Arbitrum child chain. This assumes your token is already configured for bridging. If you need to set up bridging for a new token, see Configure token bridging.

Prerequisites​

  • Your token must already be bridgeable (registered with a gateway)
  • A wallet with the tokens you want to deposit on the parent chain
  • ETH on the parent chain to pay for gas fees
  • Familiarity with Arbitrum's token bridge architecture

Depositing tokens using the Arbitrum SDK​

The simplest way to deposit tokens is using the Arbitrum SDK:

Step 1: Set up the SDK​

import { getArbitrumNetwork, Erc20Bridger } from '@arbitrum/sdk';
import { providers, Wallet } from 'ethers';

// Set up providers and wallet
const parentProvider = new providers.JsonRpcProvider(process.env.PARENT_RPC);
const childProvider = new providers.JsonRpcProvider(process.env.CHILD_RPC);
const wallet = new Wallet(process.env.PRIVATE_KEY, parentProvider);

// Initialize the bridge
const childNetwork = await getArbitrumNetwork(childProvider);
const erc20Bridge = new Erc20Bridger(childNetwork);

Step 2: Approve the gateway​

The gateway contract needs permission to transfer your tokens:

const approveTx = await erc20Bridge.approveToken({
  parentSigner: wallet,
  erc20ParentAddress: tokenAddress,
});

const approveReceipt = await approveTx.wait();
console.log(`Approved gateway: ${approveReceipt.transactionHash}`);

Step 3: Deposit tokens​

const depositTx = await erc20Bridge.deposit({
  amount: ethers.utils.parseUnits('100', 18), // Amount to deposit
  erc20ParentAddress: tokenAddress,
  parentSigner: wallet,
  childProvider: childProvider,
});

const depositReceipt = await depositTx.wait();
console.log(`Deposit initiated: ${depositReceipt.transactionHash}`);

Step 4: Wait for child chain execution​

// Wait for the deposit to be processed on the child chain
const childResult = await depositReceipt.waitForChildTransactionReceipt(childProvider);

if (childResult.complete) {
  console.log('Deposit successful!');
  console.log(`Child chain transaction: ${childResult.message.childTxReceipt.transactionHash}`);
} else {
  console.log('Deposit failed or pending');
}

Depositing tokens manually​

If you prefer to interact with the contracts directly:

Step 1: Get contract addresses​

Find the router and gateway addresses for your network on the contract addresses page.

Step 2: Approve the gateway​

First, find which gateway will handle your token:

// Call on L1GatewayRouter
address gateway = l1GatewayRouter.getGateway(tokenAddress);

Then approve it:

// Call on your ERC-20 token contract
token.approve(gateway, amountToDeposit);

Step 3: Initiate deposit​

Call the router contract's outboundTransferCustomRefund method:

function outboundTransferCustomRefund(
    address _token,
    address _refundTo,
    address _to,
    uint256 _amount,
    uint256 _maxGas,
    uint256 _gasPriceBid,
    bytes calldata _data
) external payable returns (bytes memory)

Parameters:

  • _token: Parent chain address of the token to deposit
  • _refundTo: Address to receive excess gas refund on the child chain
  • _to: Address to receive tokens on the child chain
  • _amount: Amount of tokens to deposit
  • _maxGas: Max gas for child chain execution
  • _gasPriceBid: Gas price for child chain execution
  • _data: Encoded data containing maxSubmissionCost and extra data

Example:

const router = new ethers.Contract(routerAddress, routerABI, wallet);

// Encode the data parameter
const data = ethers.utils.defaultAbiCoder.encode(['uint256', 'bytes'], [maxSubmissionCost, '0x']);

const tx = await router.outboundTransferCustomRefund(
  tokenAddress,
  refundAddress,
  destinationAddress,
  amount,
  maxGas,
  gasPriceBid,
  data,
  { value: maxSubmissionCost + maxGas * gasPriceBid },
);

await tx.wait();

How deposits work​

When you deposit tokens:

  1. Parent chain: Your tokens are escrowed in the gateway contract (for standard tokens) or burned (for custom tokens)
  2. Message sent: A retryable ticket is created to mint/release tokens on the child chain
  3. Child chain: After a few minutes, tokens are minted/released to your address

For more details on the underlying protocol, see Token bridging overview.

Troubleshooting​

Deposit not appearing on child chain​

If your deposit doesn't appear after 10-15 minutes:

  1. Check the transaction status on the Retryables Dashboard
  2. If the retryable ticket failed, you may need to manually redeem it
  3. Check that you provided sufficient gas fees for child chain execution

"Insufficient allowance" error​

Make sure you approved the correct gateway contract (not the router). Use getGateway() to find the right gateway address.

Next steps​

Resources​