Deploy an ERC-20

This recipe deploys DemoToken, a fixed-supply ERC-20 token built on OpenZeppelin Contracts. Standard ERC-20 contracts work on Sei without changes.

Before you start

A Sei Testnet account that holds some SEI for gas. Get testnet SEI from the faucet. Use a throwaway account that holds only testnet funds.
For Foundry, the account’s private key in the PRIVATE_KEY environment variable.
For Hardhat, the private key in the Hardhat keystore, as the Hardhat guide shows.
For Remix, a browser wallet such as MetaMask.

The contract

DemoToken.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import {ERC20} from "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract DemoToken is ERC20 {
    constructor() ERC20("Demo Token", "DEMO") {
        _mint(msg.sender, 1_000_000 * 10 ** decimals());
    }
}

The constructor mints 1,000,000 DEMO to the account that deploys the contract. decimals() returns 18, so the contract stores the supply as 1,000,000 × 10¹⁸ base units.

Deploy the contract

Foundry
Hardhat
Remix

Create a project and install OpenZeppelin Contracts:

forge init demo-token
cd demo-token
forge install OpenZeppelin/openzeppelin-contracts

Save the contract as src/DemoToken.sol. Then deploy it:

forge create src/DemoToken.sol:DemoToken \
  --rpc-url https://evm-rpc-testnet.sei-apis.com \
  --private-key $PRIVATE_KEY \
  --broadcast

Foundry prints the token address after Deployed to:.

Without --broadcast, forge create only simulates the deployment. It prints the transaction, but it does not send it.

For project settings, tests, and deploy scripts, see the Foundry guide.

Start from a Hardhat 3 project that has Sei Testnet configured as the seitestnet network. The Hardhat guide shows the configuration and how to store your key in the Hardhat keystore. Then install OpenZeppelin Contracts:

npm install @openzeppelin/contracts

Save the contract as contracts/DemoToken.sol. Then describe the deployment in an Ignition module:

ignition/modules/DemoToken.ts

import { buildModule } from '@nomicfoundation/hardhat-ignition/modules';

export default buildModule('DemoTokenModule', (m) => {
  const token = m.contract('DemoToken');
  return { token };
});

Deploy the module:

npx hardhat ignition deploy ignition/modules/DemoToken.ts --network seitestnet

Ignition prints the token address next to DemoTokenModule#DemoToken.

Remix compiles and deploys from the browser, so you do not install anything. First, add Sei Testnet to your wallet:The sandbox below preloads DemoToken. Compile it on the Solidity Compiler tab. Then deploy it from the Deploy & Run tab with Environment set to Injected Provider - MetaMask. Remix shows the token address under Deployed Contracts.

Verify the source

Verification publishes your source code on Seiscan, so that anyone can read the contract. Sourcify verification does not need an API key. Replace 0xYourTokenAddress with the deployed address:

forge verify-contract \
  --verifier sourcify \
  --chain-id 1328 \
  0xYourTokenAddress \
  src/DemoToken.sol:DemoToken

npx hardhat verify sourcify --network seitestnet 0xYourTokenAddress

For Remix and the other verification options, see Verify contracts.

Read the token back

Read the token’s metadata and your balance to confirm the deployment. Replace 0xYourTokenAddress with the token address and 0xYourAddress with the deployer address.

import { createPublicClient, http, parseAbi, formatUnits } from 'viem';
import { seiTestnet } from 'viem/chains';

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

const token = '0xYourTokenAddress';
const owner = '0xYourAddress';
const abi = parseAbi([
  'function name() view returns (string)',
  'function symbol() view returns (string)',
  'function decimals() view returns (uint8)',
  'function totalSupply() view returns (uint256)',
  'function balanceOf(address owner) view returns (uint256)',
]);

const [name, symbol, decimals, totalSupply, balance] = await Promise.all([
  client.readContract({ address: token, abi, functionName: 'name' }),
  client.readContract({ address: token, abi, functionName: 'symbol' }),
  client.readContract({ address: token, abi, functionName: 'decimals' }),
  client.readContract({ address: token, abi, functionName: 'totalSupply' }),
  client.readContract({ address: token, abi, functionName: 'balanceOf', args: [owner] }),
]);

console.log(`${name} (${symbol})`);
console.log('Total supply:', formatUnits(totalSupply, decimals));
console.log('Your balance:', formatUnits(balance, decimals));

import { ethers } from 'ethers';

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

const token = new ethers.Contract(
  '0xYourTokenAddress',
  [
    'function name() view returns (string)',
    'function symbol() view returns (string)',
    'function decimals() view returns (uint8)',
    'function totalSupply() view returns (uint256)',
    'function balanceOf(address owner) view returns (uint256)',
  ],
  provider
);
const owner = '0xYourAddress';

const [name, symbol, decimals, totalSupply, balance] = await Promise.all([
  token.name(),
  token.symbol(),
  token.decimals(),
  token.totalSupply(),
  token.balanceOf(owner),
]);

console.log(`${name} (${symbol})`);
console.log('Total supply:', ethers.formatUnits(totalSupply, decimals));
console.log('Your balance:', ethers.formatUnits(balance, decimals));

from decimal import Decimal
from web3 import Web3

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

def view(name, inputs, output):
    return {"type": "function", "name": name, "stateMutability": "view",
            "inputs": [{"name": n, "type": t} for n, t in inputs],
            "outputs": [{"name": "", "type": output}]}

abi = [
    view("name", [], "string"),
    view("symbol", [], "string"),
    view("decimals", [], "uint8"),
    view("totalSupply", [], "uint256"),
    view("balanceOf", [("owner", "address")], "uint256"),
]
token = w3.eth.contract(address="0xYourTokenAddress", abi=abi)
owner = "0xYourAddress"

scale = Decimal(10) ** token.functions.decimals().call()
print(f"{token.functions.name().call()} ({token.functions.symbol().call()})")
print("Total supply:", Decimal(token.functions.totalSupply().call()) / scale)
print("Your balance:", Decimal(token.functions.balanceOf(owner).call()) / scale)

You are done when you see:

Demo Token (DEMO)
Total supply: 1000000
Your balance: 1000000

ethers prints 1000000.0, because formatUnits in ethers always includes a decimal place.

ERC-20 interaction: transfers, approvals, and allowances
Listen to events: stream the token’s Transfer events
Deploy and verify: deploy any contract with viem, ethers, Foundry, or Hardhat

Overview

Client Setup

Accounts and Transactions

Tokens

Contracts

Sei Features

Before you start

The contract

Deploy the contract

Verify the source

Read the token back

​Before you start

​The contract

​Deploy the contract

​Verify the source

​Read the token back

​Related recipes

Before you start

The contract

Deploy the contract

Verify the source

Read the token back

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