viem Quickstart

Using viem with Sei in a Node.js script, CLI tool, or backend service

viem Quickstart

This example shows how to use viem with Sei outside of a React context — in a Node.js script, CLI tool, or backend service. For React apps, see wagmi and the frontend guide.

Install

npm install viem @sei-js/precompiles

Public Client

A public client handles all read-only operations.

import { createPublicClient, http } from 'viem';
import { sei } from '@sei-js/precompiles/viem';

const client = createPublicClient({
  chain: sei,
  transport: http(),
});

To use a custom RPC endpoint, pass the URL to http():

const client = createPublicClient({
  chain: sei,
  transport: http('https://evm-rpc.sei-apis.com'),
});

Reading Chain Data

const blockNumber = await client.getBlockNumber();

const block = await client.getBlock({ blockTag: 'latest' });

const balance = await client.getBalance({ address: '0xYourAddress' });

const nonce = await client.getTransactionCount({ address: '0xYourAddress' });

Wallet Client

A wallet client handles signing and broadcasting transactions.

import { createWalletClient, http } from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { sei } from '@sei-js/precompiles/viem';

const account = privateKeyToAccount('0xYourPrivateKey');

const walletClient = createWalletClient({
  account,
  chain: sei,
  transport: http(),
});

For browser use, replace http() with custom(window.ethereum) and call walletClient.getAddresses() to get the connected account.

Sending a Transaction

import { parseEther } from 'viem';

const hash = await walletClient.sendTransaction({
  to: '0xRecipient',
  value: parseEther('1'),
});

const receipt = await client.waitForTransactionReceipt({ hash });
// receipt is final immediately — Sei has instant finality

Reading a Contract

import { parseAbi } from 'viem';

const abi = parseAbi(['function balanceOf(address owner) view returns (uint256)']);

const balance = await client.readContract({
  address: '0xTokenAddress',
  abi,
  functionName: 'balanceOf',
  args: ['0xYourAddress'],
});

Writing to a Contract

const hash = await walletClient.writeContract({
  address: '0xTokenAddress',
  abi,
  functionName: 'transfer',
  args: ['0xRecipient', 1_000_000n],
});

const receipt = await client.waitForTransactionReceipt({ hash });

Simulating Before Writing

const { result } = await client.simulateContract({
  address: '0xTokenAddress',
  abi,
  functionName: 'transfer',
  args: ['0xRecipient', 1_000_000n],
  account,
});

// If simulation succeeds, execute it
const hash = await walletClient.writeContract(result);

Estimating Gas

Always use estimateGas rather than hard-coding values. SSTORE costs on Sei are governance-adjustable.

const gas = await client.estimateGas({
  account,
  to: '0xContractAddress',
  data: '0xCalldata',
});

Next Steps

• ERC-20 interaction — full token read/write examples
• ERC-721 interaction — NFT ownership, transfers, and approvals
• Pointer contracts — interact with CosmWasm tokens via ERC interfaces
• WebSocket connections — real-time block and event subscriptions