Browser Extension Wallet

Browser Extension Wallet - SDK

Prerequisites

If you haven’t downloaded the KC Wallet browser extension yet, please go to the download page:

If you have already installed the extension, check whether it is running properly in your browser. Copy the following code into the browser Developer Console:

If it runs correctly, proceed to the next step.

EVM Chains

Standard Wallet Methods

Method	Params	Return Type	Description
enable	-	Promise	Connect method; returns account information
isConnected	-	boolean	Gets connection status
request	(payload, callback)	Promise	Generic eth call. payload.method can be personal_sign, eth_sendTransaction, eth_accounts, etc. callback is invoked after execution
_isConnected	Whether connected to current Dapp	boolean	Whether connected to the current Dapp
chainId	Current connected chain ID	string	Hex-encoded chain id
networkVersion	Current connected chain ID	string	String representation of chain id

Create Connection

To connect a wallet, you can initiate a “wallet connection” using the code below by calling eth_requestAccounts to access the user’s account address.

Listen for Account Address Changes

You can listen for changes via events:

Whenever the return value of the eth_accounts RPC method changes, KC Wallet emits the corresponding event to notify the DApp of address changes. eth_accounts returns either an empty array or an array containing a single account address. If present, the returned address is the most recently used account address that the caller is permitted to access.

Because callers are identified by their URL origin, sites with the same origin share the same permissions. Whenever the user’s exposed account address changes, accountsChanged will be emitted.

Get chainId

All RPC requests are submitted to the currently connected network, so accurately obtaining the user’s chain ID is critical for EVM-based application development.

Use eth_chainId to get the user’s current chain ID:

Listen to the chainChanged event to detect network changes:

Chain IDs

Below are the Ethereum-compatible chain IDs supported by KC Wallet by default. For more information, see chainid.network.

Hex	Dec	Network
0x1	1	Ethereum Main Network (Mainnet)
0x4115	166610G	0G
0x38	56	BNB Smart Chain
0xa4b1	42161	Arbitrum One
0xa86a	43114	Avalanche C
0x2105	8453	Base
0x138de	80094	Berachain
0x659	1625	Gravity Alpha
0x3e7	999	HyperEVM
0x141	321	KuCoin Community Chain
0x8f	143	Monad
0x279f	10143	Monad Testnet
0xa	10	Optimism
0x18232	98866	Plume
0x89	137	Polygon
0x531	1329	Sei EVM
0x13a7	5031	Somnia
0xc4	196	XLayer

Switch Chain

To switch the chain that the wallet and DApp are connected to, use the example below:

Message Signing

Sign Arbitrary Messages

personal_sign (often referred to as signPersonalMessage ) is used to sign arbitrary text messages with the user’s Ethereum private key.

Sign Structured Data

eth_signTypedData (specifically eth_signTypedData_v4 ) is used to sign structured data according to the EIP-712 standard. This standard enables applications to create cryptographic signatures for complex, structured data, ensuring signatures are both human-readable and verifiable.

Sign Transactions

A transaction is a formal action on the blockchain. In KC Wallet, transactions must be initiated by calling eth_sendTransaction . Transactions may involve simple ETH transfers, token transfers, deploying a new smart contract, or changing on-chain state in any manner. Such transactions must be initiated with a signature from an externally owned account (or a simple keypair).

In KC Wallet, you can initiate a transaction via kcwallet.request .

Parameters

This section introduces transaction parameters covered in this document. Most transaction parameters in this document are handled by OKX Wallet. Transactions are divided into legacy transactions and EIP-1559 transactions, described below.

Legacy Transaction

EIP-1559 Transaction

For EIP-1559 transactions, the key difference from legacy transactions is that maxPriorityFeePerGas and maxFeePerGas are used instead of gasPrice.

maxPriorityFeePerGas (optional): An additional tip the user is willing to pay to the miner/validator to incentivize prioritizing the transaction.

maxFeePerGas (optional): The maximum total fee per unit of gas the user is willing to pay, including both the base fee and the priority fee.

Browser Extension Wallet