Bridge ERC-20 Tokens

How to deploy and bridge an ERC-20 token from Ethereum to MegaETH using the OP Stack Standard Bridge.

MegaETH's canonical bridge supports ERC-20 token bridging via the OP Stack Standard Bridge. Bridging locks tokens in the L1StandardBridge on Ethereum and mints a paired OptimismMintableERC20 on MegaETH.

Prerequisites

• Foundry installed (forge and cast)
• A wallet funded with ETH on both L1 (for deployment and bridging gas) and L2 (for registration gas)
• An ERC-20 contract ready to deploy, or an existing L1 token address

Contract Addresses

Mainnet

Contract	Chain	Address
L1StandardBridge	Ethereum (chain 1)	0x0CA3A2FBC3D770b578223FBB6b062fa875a2eE75
OptimismMintableERC20Factory	Ethereum (chain 1)	0xF875030B9464001fC0f964E47546b0AFEEbD7C61
L2StandardBridge	MegaETH Mainnet (chain 4326)	0x4200000000000000000000000000000000000010
OptimismMintableERC20Factory	MegaETH Mainnet (chain 4326)	0x4200000000000000000000000000000000000012

Testnet (Sepolia)

Steps

1

Deploy your ERC-20 on L1

Deploy your token contract on Ethereum (or Sepolia for testing). The example below uses a Foundry script; adapt it for your own token.

forge script script/Deploy.s.sol \
  --rpc-url $L1_RPC \
  --broadcast \
  --private-key $PRIVATE_KEY

Save the deployed token address — you will need it in the next step.

2

Register the L2 counterpart

Call createOptimismMintableERC20 on the OptimismMintableERC20Factory on MegaETH. This deploys a bridgeable ERC-20 on L2 that is linked to your L1 token. Replace "MyToken" and "MTK" with your token's name and symbol.

cast send $L2_MINTABLE_FACTORY \
  "createOptimismMintableERC20(address,string,string)" \
  $L1_TOKEN "MyToken" "MTK" \
  --rpc-url $L2_RPC \
  --private-key $PRIVATE_KEY

The factory emits an OptimismMintableERC20Created(address indexed localToken, address indexed remoteToken, address deployer) event. Parse the localToken field from the receipt to get your L2 token address.

# Extract the L2 token address from the event logs
# topics[0] is keccak256("OptimismMintableERC20Created(address,address,address)")
# topics[1] is the L2 token address ABI-encoded as a 32-byte padded value; [26:] strips the leading zeros
cast receipt $TX_HASH --rpc-url $L2_RPC --json \
  | jq -r '.logs[] | select(.topics[0] == "0x52fe89dd5930f343d25650b62fd367bae47088bcddffd2a88350a6ecdd620cdb") | "0x" + .topics[1][26:]'

3

Approve the L1 bridge

Approve L1StandardBridge to spend the tokens you want to bridge. Set $AMOUNT in wei (e.g. 100000000000000000000 for 100 tokens with 18 decimals).

cast send $L1_TOKEN \
  "approve(address,uint256)" \
  $L1_BRIDGE $AMOUNT \
  --rpc-url $L1_RPC \
  --private-key $PRIVATE_KEY

4

Bridge tokens to MegaETH

Call bridgeERC20 on L1StandardBridge. Pass both the L1 and L2 token addresses, the amount in wei, a minimum gas limit for L2 execution, and empty extra data.

cast send $L1_BRIDGE \
  "bridgeERC20(address,address,uint256,uint32,bytes)" \
  $L1_TOKEN \
  $L2_TOKEN \
  $AMOUNT \
  200000 \
  0x \
  --rpc-url $L1_RPC \
  --private-key $PRIVATE_KEY

200000 is sufficient for most standard ERC-20 tokens. The bridge transaction locks tokens on L1 and relays a message to MegaETH to mint the equivalent amount on L2.

5

Verify the L2 balance

After the L1 transaction is finalized and relayed (~1–2 minutes), check the balance on MegaETH.

cast call $L2_TOKEN \
  "balanceOf(address)(uint256)" \
  $(cast wallet address --private-key $PRIVATE_KEY) \
  --rpc-url $L2_RPC

The deposit takes approximately 1–2 minutes to appear on MegaETH — one L1 block for finality, plus sequencer relay time. You can track the L1 transaction on Etherscan (mainnet) or Sepolia Etherscan (testnet), and the L2 deposit on MegaETH Blockscout (mainnet) or the testnet explorer.

Withdrawals (L2 → L1)

Withdrawing tokens back to Ethereum requires initiating a withdrawal on L2 and then proving and finalizing it on L1 after the challenge period. This follows the standard OP Stack withdrawal flow — see the OP Stack withdrawal guide for details.