Deploy an ERC-20

Write an ERC-20 token with OpenZeppelin Contracts, deploy it to Sei Testnet with Foundry, Hardhat, or Remix, then verify it and read it back.

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

Run these commands to create a project, install OpenZeppelin Contracts, and write the import remappings to remappings.txt:

forge init demo-token
cd demo-token
forge install OpenZeppelin/openzeppelin-contracts
forge remappings > remappings.txt

remappings.txt maps @openzeppelin/contracts/ to the installed library. Foundry finds that mapping on its own, but editors and other Solidity tools read it from this file.

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.

Hardhat

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

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:

Foundry

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

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

Read the token back

To confirm the deployment, read the token’s metadata and your balance. First, install a client library:

viem

npm install viem

The TypeScript examples use top-level await. Save each one as a .mts file, such as script.mts. Run it with npx tsx script.mts on Node.js 18 or later. In a new npm project, tsx compiles a plain .ts file as CommonJS, where top-level await does not work.

Replace 0xYourTokenAddress with the token address and 0xYourAddress with the deployer address:

viem

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));

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.

Related recipes

• 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