ethers v6 Quickstart

Using ethers v6 with Sei in a Node.js script or browser context

ethers v6 Quickstart

This example covers ethers v6 with Sei. The patterns apply whether you are writing a Node.js script, a CLI tool, or a browser app.

Install

npm install ethers

Read-Only Provider

import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider('https://evm-rpc.sei-apis.com');

Reading Chain Data

This is the first milestone — it needs no private key.

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

const balance = await provider.getBalance('0xYourAddress'); // bigint, wei
console.log('Balance (SEI):', ethers.formatEther(balance));

const nonce = await provider.getTransactionCount('0xYourAddress'); // number
console.log('Nonce:', nonce);

You’re done when you see:

Block number: 148203117
Balance (SEI): 12.5
Nonce: 7

The exact numbers are illustrative — your block number and balance will differ. getBlockNumber() and getTransactionCount() return a number, while getBalance() returns a bigint in wei (format it with ethers.formatEther()).

Browser Provider

In a browser context, connect to the user’s injected wallet:

const provider = new ethers.BrowserProvider(window.ethereum);
const signer = await provider.getSigner();
const address = await signer.getAddress();

Wallet from Private Key

For scripts and backend services:

const wallet = new ethers.Wallet('0xYourPrivateKey', provider);

Sending a Transaction

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

const tx = await wallet.sendTransaction({
  to: '0xRecipient',
  value: ethers.parseEther('1'),
});

const receipt = await tx.wait();
// receipt is final immediately — Sei has instant finality

Reading a Contract

const abi = ['function balanceOf(address owner) view returns (uint256)'];
const contract = new ethers.Contract('0xTokenAddress', abi, provider);

const balance = await contract.balanceOf('0xYourAddress');

Writing to a Contract

Pass a signer (wallet or browser signer) to the contract constructor for write operations:

const contract = new ethers.Contract('0xTokenAddress', abi, wallet);

const tx = await contract.transfer('0xRecipient', 1_000_000n);
const receipt = await tx.wait();

Estimating Gas

const gas = await provider.estimateGas({
  from: wallet.address,
  to: '0xContractAddress',
  data: '0xCalldata',
});

Listening for Events

contract.on('Transfer', (from, to, value) => {
  console.log('Transfer:', { from, to, value });
});

// Stop listening
contract.off('Transfer');

Using Python (web3.py)

Sei is fully EVM-compatible, so any standard Ethereum client works — including Python’s web3.py.

pip install web3

from web3 import Web3

w3 = Web3(Web3.HTTPProvider("https://evm-rpc.sei-apis.com"))

print("Connected:", w3.is_connected())
print("Latest block:", w3.eth.block_number)
print("Chain ID:", w3.eth.chain_id)  # 1329

You’re done when you see:

Connected: True
Latest block: 148203117
Chain ID: 1329

The block number is illustrative; the chain ID is always 1329 on mainnet.

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