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

These snippets are TypeScript. Run any of them with no separate build step using tsx (Node 18+):

npx tsx script.ts

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.

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

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

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

const nonce = await provider.getTransactionCount(address); // 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()).

Try it live

Run these read-only calls against Sei mainnet right now — no install, no private key. They’re plain JSON-RPC, the same reads the script above performs.

Edit and run

Edit and re-run the full ethers code from this page live in the browser — a real ethers v6 JsonRpcProvider reading Sei testnet (atlantic-2), so its block number and balances won’t match the mainnet reads above:

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');

Next Steps

• Python quickstart (web3.py) — the same first steps in Python
• 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