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Version: Endpoint V2 Docs

OKX Testnet OFT Quickstart

Welcome! In this guide you'll mint and transfer a lightweight Omnichain Fungible Token (OFT) between OKX Testnet and any other supported chain.

Project scaffold​

LayerZero's CLI lets you spin up an OFT workspace in seconds:

npx create-lz-oapp@latest       # choose → "OFT example"

The wizard creates a repo with Hardhat + Foundry, sample contracts, tests and LayerZero helper scripts.

Add private keys​

Rename .env.example file to .env and update it with needed configurations:

PRIVATE_KEY = your_private_key; // Required

At a minimum, you need to have the PRIVATE_KEY. RPC URLs are optional, but strongly recommended. If you don't provide them, public RPCs will be used, but public RPCs can be unreliable or slow, leading to long waiting times for transactions to be confirmed or, at worst, cause your transactions to fail.

Hardhat network config​

Update your hardhat.config.ts file to include the networks you want to deploy your contracts to:

networks: {
  // the network you are deploying to or are already on
  // OKX Testnet (EID=40155)
  'okx-testnet': {
    eid: EndpointId.OKX_V2_TESTNET,
    url: process.env.RPC_URL_OKX || 'https://INSERT-RPC',
    accounts,
  },
  // another network you want to connect to
  'optimism-testnet': {
    eid: EndpointId.OPTSEP_V2_TESTNET,
    url: process.env.RPC_URL_OP_SEPOLIA || 'https://optimism-sepolia.gateway.tenderly.co',
    accounts,
  },
}

LayerZero wiring config​

Modify your layerzero.config.ts file to include the chains and channel security settings you want for each connection:

import {EndpointId} from '@layerzerolabs/lz-definitions';
import type {OmniPointHardhat} from '@layerzerolabs/toolbox-hardhat';
import {OAppEnforcedOption} from '@layerzerolabs/toolbox-hardhat';
import {ExecutorOptionType} from '@layerzerolabs/lz-v2-utilities';
import {TwoWayConfig, generateConnectionsConfig} from '@layerzerolabs/metadata-tools';

const okxContract: OmniPointHardhat = {
  eid: EndpointId.OKX_V2_TESTNET,
  contractName: 'MyOFT',
};

const optimismContract: OmniPointHardhat = {
  eid: EndpointId.OPTSEP_V2_TESTNET,
  contractName: 'MyOFT',
};

// To connect all the above chains to each other, we need the following pathways:
// Optimism <-> okx
// okx    <-> Optimism

// For this example's simplicity, we will use the same enforced options values for sending to all chains
// To learn more, read https://docs.layerzero.network/v2/concepts/applications/oapp-standard#execution-options-and-enforced-settings
const EVM_ENFORCED_OPTIONS: OAppEnforcedOption[] = [
  {
    msgType: 1,
    optionType: ExecutorOptionType.LZ_RECEIVE,
    gas: 80000,
    value: 0,
  },
];

const pathways: TwoWayConfig[] = [
  [
    // 1) Chain B's contract (e.g. Optimism)
    optimismContract,

    // 2) Chain A's contract (e.g. okx)
    okxContract,

    // 3) Channel security settings:
    //    • first array = "required" DVN names
    //    • second array = "optional" DVN names array + threshold
    //    • third value = threshold (i.e., number of optionalDVNs that must sign)
    //    [ requiredDVN[], [ optionalDVN[], threshold ] ]
    [['LayerZero Labs' /* ← add more DVN names here */], []],

    // 4) Block confirmations:
    //    [confirmations for Optimism → okx, confirmations for okx → Optimism]
    [1, 1],

    // 5) Enforced execution options:
    //    [options for Optimism → okx, options for okx → Optimism]
    [EVM_ENFORCED_OPTIONS, EVM_ENFORCED_OPTIONS],
  ],
];

export default async function () {
  // Generate the connections config based on the pathways
  const connections = await generateConnectionsConfig(pathways);
  return {
    contracts: [{contract: optimismContract}, {contract: okxContract}],
    connections,
  };
}
caution

It is strongly recommended to review LayerZero's Channel Security Model and understand the impact of each of these configuration settings.

See Next Steps to review the available providers and security settings.

The token contract​

contracts/MyOFT.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.22;

import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";
import { OFT }      from "@layerzerolabs/oft-evm/contracts/OFT.sol";

contract MyOFT is OFT, Ownable {
  constructor(string memory name, string memory symbol, address endpoint, address owner)
    OFT(name, symbol, endpoint, owner) Ownable(owner) {}
}
tip

The OFT contract uses the ERC20 token standard. You may want to add a mint(...) function in the constructor(...) or contract body if this is your first time deploying an OFT. If you have an existing ERC20 token, you will want to use an OFT Adapter contract.

You can read the general OFT Quickstart for a better understanding of how OFTs work and what contracts to use.

Deploy​

npx hardhat lz:deploy                     # choose okx-testnet

You will be presented with a list of networks to deploy to.

Fund your deployer with native gas tokens beforehand.

Connect the chains​

npx hardhat lz:oapp:wire   --oapp-config layerzero.config.ts

Verify peers:

npx hardhat lz:oapp:peers:get --oapp-config layerzero.config.ts

Transfer​

Calling send​

Since the send logic has already been defined, we'll instead view how the function should be called.

import {task} from 'hardhat/config';
import {getNetworkNameForEid, types} from '@layerzerolabs/devtools-evm-hardhat';
import {EndpointId} from '@layerzerolabs/lz-definitions';
import {addressToBytes32} from '@layerzerolabs/lz-v2-utilities';
import {Options} from '@layerzerolabs/lz-v2-utilities';
import {BigNumberish, BytesLike} from 'ethers';

interface Args {
  amount: string;
  to: string;
  toEid: EndpointId;
}

interface SendParam {
  dstEid: EndpointId; // Destination endpoint ID, represented as a number.
  to: BytesLike; // Recipient address, represented as bytes.
  amountLD: BigNumberish; // Amount to send in local decimals.
  minAmountLD: BigNumberish; // Minimum amount to send in local decimals.
  extraOptions: BytesLike; // Additional options supplied by the caller to be used in the LayerZero message.
  composeMsg: BytesLike; // The composed message for the send() operation.
  oftCmd: BytesLike; // The OFT command to be executed, unused in default OFT implementations.
}

// send tokens from a contract on one network to another
task('lz:oft:send', 'Sends tokens from either OFT or OFTAdapter')
  .addParam('to', 'contract address on network B', undefined, types.string)
  .addParam('toEid', 'destination endpoint ID', undefined, types.eid)
  .addParam('amount', 'amount to transfer in token decimals', undefined, types.string)
  .setAction(async (taskArgs: Args, {ethers, deployments}) => {
    const toAddress = taskArgs.to;
    const eidB = taskArgs.toEid;

    // Get the contract factories
    const oftDeployment = await deployments.get('MyOFT');

    const [signer] = await ethers.getSigners();

    // Create contract instances
    const oftContract = new ethers.Contract(oftDeployment.address, oftDeployment.abi, signer);

    const decimals = await oftContract.decimals();
    const amount = ethers.utils.parseUnits(taskArgs.amount, decimals);
    let options = Options.newOptions().addExecutorLzReceiveOption(65000, 0).toBytes();

    // Now you can interact with the correct contract
    const oft = oftContract;

    const sendParam: SendParam = {
      dstEid: eidB,
      to: addressToBytes32(toAddress),
      amountLD: amount,
      minAmountLD: amount,
      extraOptions: options,
      composeMsg: ethers.utils.arrayify('0x'), // Assuming no composed message
      oftCmd: ethers.utils.arrayify('0x'), // Assuming no OFT command is needed
    };
    // Get the quote for the send operation
    const feeQuote = await oft.quoteSend(sendParam, false);
    const nativeFee = feeQuote.nativeFee;

    console.log(
      `sending ${taskArgs.amount} token(s) to network ${getNetworkNameForEid(eidB)} (${eidB})`,
    );

    const ERC20Factory = await ethers.getContractFactory('ERC20');
    const innerTokenAddress = await oft.token();

    // // If the token address !== address(this), then this is an OFT Adapter
    // if (innerTokenAddress !== oft.address) {
    //     // If the contract is OFT Adapter, get decimals from the inner token
    //     const innerToken = ERC20Factory.attach(innerTokenAddress);

    //     // Approve the amount to be spent by the oft contract
    //     await innerToken.approve(oftDeployment.address, amount);
    // }

    const r = await oft.send(sendParam, {nativeFee: nativeFee, lzTokenFee: 0}, signer.address, {
      value: nativeFee,
    });
    console.log(`Send tx initiated. See: https://layerzeroscan.com/tx/${r.hash}`);
  });

Done!​

You've issued an omnichain token and bridged it from OKX Testnet to Optimism. Customize supply logic, fees, or add more chains by applying changes to the core contract, redeploying, and repeating the wiring step.

Troubleshooting​

If your quoteSend call reverts, it usually means that your LayerZero wiring hasn't been fully configured or there's no default pathway for the chains you're trying to bridge. Here's how to diagnose and fix it:

  1. Wiring Didn't Succeed
    Run the following to inspect your on‑chain wiring configuration:

    npx hardhat lz:oapp:config:get --oapp-config layerzero.config.ts

    See that your source configuration has a valid send library, DVN address, and target eid.

  2. No Default Pathway
    LayerZero default settings should be considered placeholders. Sometimes the LayerZero defaults will contain a LzDeadDVN. Those entries indicate that a default pathway setting does not exist.

    • Check: You can see if your configuration contains a LzDeadDVN by viewing the Default Config Checker on LayerZero Scan.

    • Fix: Open your layerzero.config.ts and under the relevant pathways entry, add working DVN providers (in the [ requiredDVN[], [ optionalDVN[], threshold ] ] section).

    • Re-run your wiring command for the connections so that the wiring on both chains is live.

      [
        optimismContract,
        currentContract,
        [['LayerZero Labs'], []], // required & optional DVNs
        [1, 1],                     // required block confirmations
        [EVM_ENFORCED_OPTIONS, EVM_ENFORCED_OPTIONS],
      ],

Once you've updated your config, retry your quoteSend flow. It should now return a fee estimate instead of reverting.

Next steps​