Developer tools

Retrieve detailed information on address and token authorizations. Utilize API tools for domain risk detection, on-chain transaction broadcasting, and contract verification for both proxy and standard contracts.

Contract verification

Source code verification provides a way for projects to open source their smart contract code for end users to inspect and verify that it does what it claims to do and improve the transparency.

Endpoints of the "Contract verification" module support submitting contract source code for contract verification, verifying proxy contracts, and querying the contract ABI and source code of already verified contracts.

Verify contract source code

By uploading the contract source code, OKLink explorer will match the compiled contract bytecode with the bytecode on the blockchain and display it on the contract page of the explorer.

You can use this endpoint to quickly verify contracts and improve verification efficiency. The average processing time for contract verification is between 30-60 seconds.

Consumption per query 0

HTTP Request

POST /api/v5/explorer/contract/verify-source-code

Request Example

POST /api/v5/explorer/contract/verify-source-code
body
{
    "chainShortName":"ETH",
    "contractAddress":"0x9Dca580D2c8B8e19e9d77345a5b4C2820B25b386",
    "contractName":"HelloWorld",
    "sourceCode":"pragma solidity ^0.7.6;↵contract HelloWorl {↵ string public greet = 'Hello Worl!';↵}",
    "codeFormat":"solidity-single-file",
    "compilerVersion":"v0.7.6+commit.7338295f",
    "optimization":"1",
    "optimizationRuns":"200",
    "contractAbi":"0xfce353f66162630000000000000000000000000",
    "evmVersion":"tangerineWhistle",
    "viaIr":false,
    "libraryInfo":[
        {
        "libraryName":"libraryName1",
        "libraryAddress":"0xCfE28868F6E0A24b7333D22D8943279e76aC2cdc"
        },
        {
        "libraryName":"libraryName2",
        "libraryAddress":"0xCfE28868F6E0A24b7333D22D8943279e76aC2cdc"
        },
        {
        "libraryName":"libraryName3",
        "libraryAddress":"0xCfE28868F6E0A24b7333D22D8943279e76aC2cdc"
        }
    ]
}

Request Parameters

Parameter	Type	Required	Description
chainShortName	String	Yes	The abbreviated name of the blockchain network
contractAddress	String	Yes	Contract address
contractName	String	Yes	Contract name
sourceCode	String	Yes	Source code of the contract. If your contract uses "imports", you will need to concatenate the code into one file (otherwise known as "flattening") as we do not support "imports" in separate files. You can use Solidity flatteners like SolidityFlattery(by@DaveAppleton)
codeFormat	String	Yes	Code format, we support `solidity-single-file`, `solidity-standard-json-input`, `vyper`
compilerVersion	String	No	Compiler version used, e.g., `v0.7.6+commit.7338295f`, `vyper:0.2.11`. You can check the supported compiler versions for contract verification in the OKLink Explorer under the Verify Contract section When the codeFormat is `solidity-standard-json-input`, it is optional; otherwise, it is required.
optimization	String	No	Whether optimization was used when compiling the contract, `0` for no optimization, `1` if optimization was used When the codeFormat is `solidity-standard-json-input`, it is optional; otherwise, it is required.
optimizationRuns	String	No	The number of runs if optimization was used, e.g., 200
contractAbi	String	No	Contract ABI
evmVersion	String	No	EVM version of contract compilation, leave blank for default compiler, specify if others such as `tangerineWhistle`, `spuriousDragon`, `byzantium`
licenseType	String	No	Open source license type, leave blank for default `No License`
viaIr	Bol	No	Whether to introduce an IR-based code generator, should be consistent with your compiling setting; `true` / `false`, `false` by default
libraryInfo	Array	No	Library info used in contract. The libraryName and libraryAddress must be matched one by one. We support up to 10 different libraries.
> libraryName	String	No	Library name
> libraryAddress	String	No	Library address, e.g., 0xCfE28868F6E0A24b7333D22D8943279e76aC2cdc

Response Example

{
    "code": "0",
    "msg": "",
    "data": [
        "eb5c06099d3841359d398541166343fe"
    ]
}

Response Parameters

Parameter	Type	Description
guid	String	A GUID is returned upon successful submission, which can be used to query the verification result

Get contract source code verification results

After submitting the source code verification, you can query the result with the GUID returned.

Consumption per query 0

HTTP Request

POST /api/v5/explorer/contract/check-verify-result

Request Example

POST /api/v5/explorer/contract/check-verify-result
body
{
    "chainShortName":"ETH",
    "guid":"eb5c06099d3841359d398541166343fe"
}

Request Parameters

Parameter	Type	Required	Description
chainShortName	String	Yes	The abbreviated name of the blockchain network
guid	String	Yes	Query the source code verification result with the GUID returned

Response Example

{
    "code": "0",
    "msg": "",
    "data": [
        "Success"
    ]
}

Response Parameters

Parameter	Type	Description
result	String	Contract source code verification result `Success`,`Fail`,`Pending`

Verify proxy contract

Verify whether a proxy contract implements the contract as expected.

Consumption per query 0

HTTP Request

POST /api/v5/explorer/contract/verify-proxy-contract

Request Example

POST /api/v5/explorer/contract/verify-proxy-contract
body
{
    "chainShortName": "ETH",
    "proxyContractAddress": "0xfeee12d53ddb7ce61ee467ddf7243212a953174a",
    "expectedImplementation": "0x0ecbefc71524068cf18f9d4e50d787e134ee70b8"
}

Request Parameters

Parameter	Type	Required	Description
chainShortName	String	Yes	The abbreviated name of the blockchain network
proxyContractAddress	String	Yes	Proxy contract address
expectedImplementation	String	No	Verify whether the implementation contract for the proxy contract is this address

Response Example

{
    "code": "0",
    "msg": "",
    "data": [
        "4f2e75682f75410f958c0a3bbf754358"
    ]
}

Response Parameters

Parameter	Type	Description
guid	String	A GUID is returned upon successful submission, which can be used to query the verification result

Get proxy contract verification results

After submitting the proxy contract verification, you can query the result with the GUID returned.

Consumption per query 0

HTTP Request

POST /api/v5/explorer/contract/check-proxy-verify-result

Request Example

POST /api/v5/explorer/contract/check-proxy-verify-result
body
{
    "chainShortName":"ETH",
    "guid":"4f2e75682f75410f958c0a3bbf754358"
}

Request Parameters

Parameter	Type	Required	Description
chainShortName	String	Yes	The abbreviated name of the blockchain network
guid	String	Yes	Query the proxy contract verification result with the GUID returned

Response Example

{
    "code": "0",
    "msg": "The proxy's (0x826427966fb2e7edee940c5d99b7d66062faef2e) implementation contract is found at 0xd4a2dca4e03713d5bf7d2173237058466a9c1be4 and is successfully updated.",
    "data": []
}

Response Parameters

Parameter	Type	Description
result	String	Proxy contract verification result. If the verification is successful, return the address of the implementation contract. If the verification fails, return "A corresponding implementation contract was unfortunately not detected for the proxy address."

Get verified contract's ABI and source code

Query the contract ABI, source code and other basic information of the verified contract, or query the implementation contract address information of the verified proxy contract.

Consumption per query 0

HTTP Request

GET /api/v5/explorer/contract/verify-contract-info

Request Example

/api/v5/explorer/contract/verify-contract-info?chainShortName=ETH&contractAddress=0xcF80631b469A54dcba8c8ee1aF84505f496ed248

Request Parameters

Parameter	Type	Required	Description
chainShortName	String	Yes	The abbreviated name of the blockchain network
contractAddress	String	Yes	Contract address

Response Example

{
    "code": "0",
    "msg": "",
    "data": [
        {
            "sourceCode": "// proxy.sol - execute actions atomically through the proxy's identity\r\n\r\n// Copyright (C) 2017  DappHub, LLC\r\n\r\n// This program is free software: you can redistribute it and/or modify\r\n// it under the terms of the GNU General Public License as published by\r\n// the Free Software Foundation, either version 3 of the License, or\r\n// (at your option) any later version.\r\n\r\n// This program is distributed in the hope that it will be useful,\r\n// but WITHOUT ANY WARRANTY; without even the implied warranty of\r\n// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r\n// GNU General Public License for more details.\r\n\r\n// You should have received a copy of the GNU General Public License\r\n// along with this program.  If not, see <http://www.gnu.org/licenses/>.\r\n\r\npragma solidity ^0.4.23;\r\n\r\ncontract DSAuthority {\r\n    function canCall(\r\n        address src, address dst, bytes4 sig\r\n    ) public view returns (bool);\r\n}\r\n\r\ncontract DSAuthEvents {\r\n    event LogSetAuthority (address indexed authority);\r\n    event LogSetOwner     (address indexed owner);\r\n}\r\n\r\ncontract DSAuth is DSAuthEvents {\r\n    DSAuthority  public  authority;\r\n    address      public  owner;\r\n\r\n    constructor() public {\r\n        owner = msg.sender;\r\n        emit LogSetOwner(msg.sender);\r\n    }\r\n\r\n    function setOwner(address owner_)\r\n        public\r\n        auth\r\n    {\r\n        owner = owner_;\r\n        emit LogSetOwner(owner);\r\n    }\r\n\r\n    function setAuthority(DSAuthority authority_)\r\n        public\r\n        auth\r\n    {\r\n        authority = authority_;\r\n        emit LogSetAuthority(authority);\r\n    }\r\n\r\n    modifier auth {\r\n        require(isAuthorized(msg.sender, msg.sig));\r\n        _;\r\n    }\r\n\r\n    function isAuthorized(address src, bytes4 sig) internal view returns (bool) {\r\n        if (src == address(this)) {\r\n            return true;\r\n        } else if (src == owner) {\r\n            return true;\r\n        } else if (authority == DSAuthority(0)) {\r\n            return false;\r\n        } else {\r\n            return authority.canCall(src, this, sig);\r\n        }\r\n    }\r\n}\r\n\r\ncontract DSNote {\r\n    event LogNote(\r\n        bytes4   indexed  sig,\r\n        address  indexed  guy,\r\n        bytes32  indexed  foo,\r\n        bytes32  indexed  bar,\r\n        uint              wad,\r\n        bytes             fax\r\n    ) anonymous;\r\n\r\n    modifier note {\r\n        bytes32 foo;\r\n        bytes32 bar;\r\n\r\n        assembly {\r\n            foo := calldataload(4)\r\n            bar := calldataload(36)\r\n        }\r\n\r\n        emit LogNote(msg.sig, msg.sender, foo, bar, msg.value, msg.data);\r\n\r\n        _;\r\n    }\r\n}\r\n\r\n// DSProxy\r\n// Allows code execution using a persistant identity This can be very\r\n// useful to execute a sequence of atomic actions. Since the owner of\r\n// the proxy can be changed, this allows for dynamic ownership models\r\n// i.e. a multisig\r\ncontract DSProxy is DSAuth, DSNote {\r\n    DSProxyCache public cache;  // global cache for contracts\r\n\r\n    constructor(address _cacheAddr) public {\r\n        require(setCache(_cacheAddr));\r\n    }\r\n\r\n    function() public payable {\r\n    }\r\n\r\n    // use the proxy to execute calldata _data on contract _code\r\n    function execute(bytes _code, bytes _data)\r\n        public\r\n        payable\r\n        returns (address target, bytes32 response)\r\n    {\r\n        target = cache.read(_code);\r\n        if (target == 0x0) {\r\n            // deploy contract & store its address in cache\r\n            target = cache.write(_code);\r\n        }\r\n\r\n        response = execute(target, _data);\r\n    }\r\n\r\n    function execute(address _target, bytes _data)\r\n        public\r\n        auth\r\n        note\r\n        payable\r\n        returns (bytes32 response)\r\n    {\r\n        require(_target != 0x0);\r\n\r\n        // call contract in current context\r\n        assembly {\r\n            let succeeded := delegatecall(sub(gas, 5000), _target, add(_data, 0x20), mload(_data), 0, 32)\r\n            response := mload(0)      // load delegatecall output\r\n            switch iszero(succeeded)\r\n            case 1 {\r\n                // throw if delegatecall failed\r\n                revert(0, 0)\r\n            }\r\n        }\r\n    }\r\n\r\n    //set new cache\r\n    function setCache(address _cacheAddr)\r\n        public\r\n        auth\r\n        note\r\n        returns (bool)\r\n    {\r\n        require(_cacheAddr != 0x0);        // invalid cache address\r\n        cache = DSProxyCache(_cacheAddr);  // overwrite cache\r\n        return true;\r\n    }\r\n}\r\n\r\n// DSProxyFactory\r\n// This factory deploys new proxy instances through build()\r\n// Deployed proxy addresses are logged\r\ncontract DSProxyFactory {\r\n    event Created(address indexed sender, address indexed owner, address proxy, address cache);\r\n    mapping(address=>bool) public isProxy;\r\n    DSProxyCache public cache = new DSProxyCache();\r\n\r\n    // deploys a new proxy instance\r\n    // sets owner of proxy to caller\r\n    function build() public returns (DSProxy proxy) {\r\n        proxy = build(msg.sender);\r\n    }\r\n\r\n    // deploys a new proxy instance\r\n    // sets custom owner of proxy\r\n    function build(address owner) public returns (DSProxy proxy) {\r\n        proxy = new DSProxy(cache);\r\n        emit Created(msg.sender, owner, address(proxy), address(cache));\r\n        proxy.setOwner(owner);\r\n        isProxy[proxy] = true;\r\n    }\r\n}\r\n\r\n// DSProxyCache\r\n// This global cache stores addresses of contracts previously deployed\r\n// by a proxy. This saves gas from repeat deployment of the same\r\n// contracts and eliminates blockchain bloat.\r\n\r\n// By default, all proxies deployed from the same factory store\r\n// contracts in the same cache. The cache a proxy instance uses can be\r\n// changed.  The cache uses the sha3 hash of a contract's bytecode to\r\n// lookup the address\r\ncontract DSProxyCache {\r\n    mapping(bytes32 => address) cache;\r\n\r\n    function read(bytes _code) public view returns (address) {\r\n        bytes32 hash = keccak256(_code);\r\n        return cache[hash];\r\n    }\r\n\r\n    function write(bytes _code) public returns (address target) {\r\n        assembly {\r\n            target := create(0, add(_code, 0x20), mload(_code))\r\n            switch iszero(extcodesize(target))\r\n            case 1 {\r\n                // throw if contract failed to deploy\r\n                revert(0, 0)\r\n            }\r\n        }\r\n        bytes32 hash = keccak256(_code);\r\n        cache[hash] = target;\r\n    }\r\n}",
            "contractName": "DSProxy",
            "compilerVersion": "v0.4.23+commit.124ca40d",
            "optimization": "1",
            "optimizationRuns": "200",
            "contractAbi": "[{\"constant\":false,\"inputs\":[{\"indexed\":false,\"name\":\"owner_\",\"type\":\"address\"}],\"name\":\"setOwner\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"indexed\":false,\"name\":\"_target\",\"type\":\"address\"},{\"indexed\":false,\"name\":\"_data\",\"type\":\"bytes\"}],\"name\":\"execute\",\"outputs\":[{\"name\":\"response\",\"type\":\"bytes32\"}],\"payable\":true,\"stateMutability\":\"payable\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"indexed\":false,\"name\":\"_code\",\"type\":\"bytes\"},{\"indexed\":false,\"name\":\"_data\",\"type\":\"bytes\"}],\"name\":\"execute\",\"outputs\":[{\"name\":\"target\",\"type\":\"address\"},{\"name\":\"response\",\"type\":\"bytes32\"}],\"payable\":true,\"stateMutability\":\"payable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"cache\",\"outputs\":[{\"name\":\"\",\"type\":\"address\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"indexed\":false,\"name\":\"authority_\",\"type\":\"address\"}],\"name\":\"setAuthority\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"owner\",\"outputs\":[{\"name\":\"\",\"type\":\"address\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"indexed\":false,\"name\":\"_cacheAddr\",\"type\":\"address\"}],\"name\":\"setCache\",\"outputs\":[{\"name\":\"\",\"type\":\"bool\"}],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"authority\",\"outputs\":[{\"name\":\"\",\"type\":\"address\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"indexed\":false,\"name\":\"_cacheAddr\",\"type\":\"address\"}],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"constructor\"},{\"constant\":false,\"payable\":true,\"stateMutability\":\"payable\",\"type\":\"fallback\"},{\"constant\":false,\"inputs\":[{\"indexed\":true,\"name\":\"sig\",\"type\":\"bytes4\"},{\"indexed\":true,\"name\":\"guy\",\"type\":\"address\"},{\"indexed\":true,\"name\":\"foo\",\"type\":\"bytes32\"},{\"indexed\":true,\"name\":\"bar\",\"type\":\"bytes32\"},{\"indexed\":false,\"name\":\"wad\",\"type\":\"uint256\"},{\"indexed\":false,\"name\":\"fax\",\"type\":\"bytes\"}],\"name\":\"LogNote\",\"payable\":false,\"type\":\"event\"},{\"constant\":false,\"inputs\":[{\"indexed\":true,\"name\":\"authority\",\"type\":\"address\"}],\"name\":\"LogSetAuthority\",\"payable\":false,\"type\":\"event\"},{\"constant\":false,\"inputs\":[{\"indexed\":true,\"name\":\"owner\",\"type\":\"address\"}],\"name\":\"LogSetOwner\",\"payable\":false,\"type\":\"event\"}]",
            "evmVersion": "Default",
            "licenseType": "No License (None)",
            "libraryInfo": "",
            "proxy": "0",
            "implementation": "",
            "swarmSource": "bzzr://e498874c9ba9e75028e0c84f1b1d83b2dad5de910c59b837b32e5a190794c5e1"
        }
    ]
}

Response Parameters

Parameter	Type	Description
sourceCode	String	Source code of the contract
contractName	String	Contract name
compilerVersion	String	Compiler version used
optimization	String	Whether optimization was used when compiling the contract, `0` for no optimization, `1` if optimization was used
optimizationRuns	String	The number of runs if optimization was used
contractAbi	String	Contract ABI
evmVersion	String	EVM version of contract compilation
licenseType	String	Open source license type
libraryInfo	Array	Library info used in contract
> libraryName	String	Library name
> libraryAddress	String	Library address, e.g., 0xCfE28868F6E0A24b7333D22D8943279e76aC2cdc
proxy	String	Whether it is a proxy contract, `0` means it is not a proxy contract, `1` means it is a proxy contract
implementation	String	The implementation contract address of the proxy contract
swarmSource	String	Swarm hash of contract source code

Contract verification plugin

OKLink supports contract verification using third-party plugins such as hardhat and truffle and foundry, greatly improving your contract verification efficiency.

The supported chains include ETH, XLAYER, XLAYER_TESTNET, BSC, POLYGON, AVAXC, FTM, OP, ARBITRUM, LINEA, MANTA, CANTO, BASE, SCROLL, OPBNB, POLYGON_ZKEVM, SEPOLIA_TESTNET, GOERLI_TESTNET, AMOY_TESTNET, MUMBAI_TESTNET, POLYGON_ZKEVM_TESTNET

Contract verification using Hardhat

Method 1 (recommended): Verify by @okxweb3/hardhat-explorer-verify plugin

1、Install the Plugin: To install this plugin in your Hardhat project, use the following command:
npm install @okxweb3/hardhat-explorer-verify

2、Configure Hardhat: In your Hardhat configuration file (usually hardhat.config.js or hardhat.config.ts), import and configure the plugin. Ensure your network configuration and API keys are correctly set.

Example：

import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";
import '@okxweb3/hardhat-explorer-verify';  // Import the plugin

const config: HardhatUserConfig = {
    solidity: "0.8.24",
    sourcify: {
        enabled: true,
    },
    networks: {
        xlayer: {
            url: "https://xlayerrpc.example.com",
            accounts: ["<Your Wallet Private Key>"],
        },
    },
    etherscan: {
        apiKey: '...'
    },
    okxweb3explorer: {
        apiKey: "<Your API Key>",
        customChains: [
            {
                network: "Fractal Bitcoin Mainnet",
                chainId: 70000061,
                urls: {
                    apiURL: "https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/FRACTAL",
                    browserURL: "https://www.oklink.com",
                }
             }
        ]
    }
};

export default config;

Custom chains can be configured based on the chains supported in openAPI https://www.oklink.com/docs/zh/#quickstart-guide-list-of-supported-chains).
customChains: [{ network: "chainName", chainId: {chainId}, urls: { apiURL: "https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/{chainShortName}", browserURL: "https://www.oklink.com", }}]

3、Verify Contracts: After deploying the contracts, use Hardhat to run the verification script. This typically involves running a specific Hardhat task that automatically fetches contract data and submits it to the OKLink blockchain explorer for verification.
Example command:
npx hardhat okverify --network xlayer <Your Contract Address>

4、View Verification Results: Once verification is successful, you can view the verification status and the contract code on the OKLink blockchain explorer.

5、Verify TransparentUpgradeableProxy Contract
Example command:
npx hardhat okverify --network xlayer --contract <Contract>:<Name> --proxy <address>

--proxy: mention it's a proxy contract address.
Note: If using 897 Contract, don't add --proxy. Directly use npx hardhat okverify --network xlayer --contract <Contract>:<Name>

You can view detailed usage and instructions in https://github.com/okx/hardhat-explorer-verify

Take the ETH chain as an example:

module.exports = {
    ...
    etherscan: {
        apiKey: {OKLink API key},
        customChains: [
            {
                network: "eth",
                chainId: 1,
                urls: {
                    apiURL: "https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/eth",
                    browserURL: "https://www.oklink.com",
                }
            }
        ]
    }
};

Method 2: Verify by making the following modifications to the hardhat.config.js file:

Set the apiKey to your OKLink API key, which can be obtained from My account - API management on https://www.oklink.com/.
Set the network to the blockchain network you have added.
Set the chainId to the ID of the chain.
Set the apiURL in the urls to https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/{chainShortName}, you can find the {chainShortName} of different chains here, and set the browserURL to https://www.oklink.com.

Contract verification using foundry

Apply for OKLink API key: https://www.oklink.com/docs/en/#quickstart-guide-getting-started

Verify a contract with the forge verify-contract command. You must provide:

the contract address
the contract name or the path to the contract :
verify-url OKLink verify API url: https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/{chainShortName}, {chainShortName} is the short name of the chain, you can see the short name of the supported chain at here, explorerUrl is https://www.oklink.com
your OKLink API key

full APIkey example：

forge verify-contract <the_contract_address>
       src/MyToken.sol:MyToken
       --verifier oklink
       --verifier-url https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/eth
       --api-key oklinkApiKey

Check verification result

It is recommended to use the --watch flag along with verify-contract command in order to poll for the verification result.
If the --watch flag was not supplied, you can check the verification status with the forge verify-check command:

example：

forge verify-check --chain 11155111 --verifier oklink --verifier-url https://www.oklink.com/api/explorer/v1/contract/verify/async/api/ethsepolia --api-key <your_OKLink_api_key>  <GUID>

Contract verification using truffle

Take the ETH chain as an example:

plugins: ['truffle-plugin-verify']
oklinkVerify: {
      provider: () => new HDWalletProvider(privateKey, infuraUrl),     // Localhost (default: none)
      gas: gasAmount,
      network_id: 1,
      verify: {
        apiUrl: 'https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/eth@truffle',
        apiKey: '{OKLink API key}',
        explorerUrl: 'https://www.oklink.com/',
      }
    },

To verify a contract using truffle plugin, you need to add the following content to the module.exports module in the configuration file:

Set the apiKey to your OKLink API key, which can be obtained from My account - API management on https://www.oklink.com/.
Set the network_id to the ID of the chain.
Set the apiURL in the urls to https://www.oklink.com/api/v5/explorer/contract/verify-source-code-plugin/{chainShortName}@truffle, you can find the {chainShortName} of different chains here, and set the explorerUrl to https://www.oklink.com.