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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.

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Install

npm install viem
These snippets are TypeScript. Run any of them with no separate build step using tsx (Node 18+): 
npx tsx script.ts

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Public Client

A public client handles all read-only operations. 
import { createPublicClient, http } from 'viem';
import { sei } from 'viem/chains';

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'),
});

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Reading Chain Data

This is the first milestone — it needs no private key. 
import { formatEther } from 'viem';

// Any valid Sei EVM address — swap in your own
const address = '0x0000000000000000000000000000000000000000';

const blockNumber = await client.getBlockNumber(); // bigint
console.log('Block number:', blockNumber);

const balance = await client.getBalance({ address }); // bigint, wei
console.log('Balance (SEI):', formatEther(balance));

const nonce = await client.getTransactionCount({ address }); // number
console.log('Nonce:', nonce);
You’re done when you see: 
Block number: 148203117n
Balance (SEI): 12.5
Nonce: 7
The exact numbers are illustrative — your block number and balance will differ. Note the trailing n: getBlockNumber() and getBalance() return bigint, while getTransactionCount() returns a number.

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Try It Live

Run these read-only calls against Sei mainnet right now — no install, no private key. They’re the same reads the script above performs, issued straight from your browser.

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Edit and run

The buttons above issue raw JSON-RPC. To run the full viem code from this page — imports, a public client, several reads — edit and re-run it live in the sandbox below. No install, no wallet, no key:

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Wallet Client

A wallet client handles signing and broadcasting transactions. 
import { createWalletClient, http } from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { sei } from 'viem/chains';

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.

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Sending a Transaction

Next step — this requires a funded account; get testnet SEI from the faucet. 
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

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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'],
});

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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 });

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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);

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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',
});

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Next Steps