💰 ERC20 Tokens

ERC20 is the standard for fungible tokens on the EVM: one token is interchangeable with another (like currency). Defined by EIP-20 .

🎯 Why ERC20

Composability — Wallets and DApps expect balanceOf, transfer, approve, allowance
Ecosystem — Uniswap , OpenZeppelin , and tooling all support ERC20
Bridges & L2s — Wrapped assets (e.g. WETH) and bridged tokens are typically ERC20

📚 Core Interface

Required (and common) functions and events:


// Minimal interface (EIP-20)
interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
 
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

📝 Minimal ERC20 Example

Using OpenZeppelin :


// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
 
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 
contract MyToken is ERC20 {
    constructor(uint256 initialSupply) ERC20("MyToken", "MTK") {
        _mint(msg.sender, initialSupply);
    }
}

🔧 Reading Balances (ethers.js v6)


import { ethers } from 'ethers';
 
const provider = new ethers.JsonRpcProvider(process.env.RPC_URL);
const tokenAddress = '0x...';
const abi = [
  'function balanceOf(address) view returns (uint256)',
  'function decimals() view returns (uint8)',
  'function symbol() view returns (string)'
];
 
const token = new ethers.Contract(tokenAddress, abi, provider);
const walletAddress = '0x...';
 
const balance = await token.balanceOf(walletAddress);
const decimals = await token.decimals();
const symbol = await token.symbol();
 
console.log(`${ethers.formatUnits(balance, decimals)} ${symbol}`);

💰 ERC20 Tokens

🎯 Why ERC20

📚 Core Interface

📝 Minimal ERC20 Example

🔧 Reading Balances (ethers.js v6)

🔗 Resources