smart-contract-reading-guide

Smart Contract Reading Guide

You don't need to be a Solidity developer to read smart contracts. This guide teaches you to understand what contracts do by reading their code on block explorers.

Finding Contract Code

Block Explorers

Chain	Explorer	URL
Ethereum	Etherscan	etherscan.io
Arbitrum	Arbiscan	arbiscan.io
Base	BaseScan	basescan.org
Optimism	Optimistic Etherscan	optimistic.etherscan.io
Polygon	PolygonScan	polygonscan.com

Steps to Read a Contract

1. Go to the explorer → Enter contract address
2. Click "Contract" tab
3. Look for the green checkmark ("Contract Source Code Verified")
4. If not verified → RED FLAG — don't interact with unverified contracts

Understanding Contract Structure

Solidity 101 for Readers

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

// Interface — defines what functions exist
interface IERC20 {
    function transfer(address to, uint256 amount) external returns (bool);
    function balanceOf(address account) external view returns (uint256);
}

// Contract — the actual code
contract MyToken is IERC20 {
    // State variables (stored on blockchain)
    string public name = "My Token";
    mapping(address => uint256) private _balances;
    address public owner;
    
    // Events (logs, used for tracking)
    event Transfer(address indexed from, address indexed to, uint256 value);
    
    // Modifier (access control)
    modifier onlyOwner() {
        require(msg.sender == owner, "Not owner");
        _;
    }
    
    // View function (read-only, free to call)
    function balanceOf(address account) external view returns (uint256) {
        return _balances[account];
    }
    
    // State-changing function (costs gas)
    function transfer(address to, uint256 amount) external returns (bool) {
        _balances[msg.sender] -= amount;
        _balances[to] += amount;
        emit Transfer(msg.sender, to, amount);
        return true;
    }
    
    // Owner-only function (⚠️ check these carefully)
    function mint(address to, uint256 amount) external onlyOwner {
        _balances[to] += amount;
    }
}