---
id: ethereum/core
name: Ethereum Core Development
version: 1.0.0
ecosystem: ethereum
type: technical-doc
time_sensitivity: evergreen
source: official
confidence: high
maintainer: AgentRel Community
last_updated: 2026-03-19
feedback_endpoint: https://agentrel.vercel.app/api/feedback
---

## Overview
Ethereum is the world's leading smart contract platform. This skill covers core development patterns, common AI mistakes, and best practices for building on Ethereum with modern tooling (ethers.js v6, Hardhat, OpenZeppelin).

## ⚠️ Gotchas (Common AI Mistakes)

### 1. Use ethers.js v6, not v5
❌ Outdated (ethers v5):
```typescript
import { ethers } from 'ethers';
const provider = new ethers.providers.Web3Provider(window.ethereum);
const signer = provider.getSigner();
```

✅ Current (ethers v6):
```typescript
import { ethers } from 'ethers';
const provider = new ethers.BrowserProvider(window.ethereum);
const signer = await provider.getSigner();
```

### 2. BigNumber → Native BigInt
❌ v5:
```typescript
const value = ethers.BigNumber.from('1000000000000000000');
const doubled = value.mul(2);
```

✅ v6:
```typescript
const value = ethers.parseEther('1.0'); // returns bigint
const doubled = value * 2n;
```

### 3. Contract factory deployment
✅ v6:
```typescript
const factory = new ethers.ContractFactory(abi, bytecode, signer);
const contract = await factory.deploy(constructorArg);
await contract.waitForDeployment();
const address = await contract.getAddress();
```

## Smart Contract Best Practices

### Use OpenZeppelin for security primitives
```solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract MyToken is ERC20, Ownable {
    constructor() ERC20("MyToken", "MTK") Ownable(msg.sender) {
        _mint(msg.sender, 1_000_000 * 10 ** decimals());
    }
}
```

## Installation
```bash
npm install ethers
npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox
npm install @openzeppelin/contracts
```

## Reference
- [Ethereum Developer Docs](https://ethereum.org/developers)
- [ethers.js v6 Migration Guide](https://docs.ethers.org/v6/migrating/)
- [OpenZeppelin Contracts](https://docs.openzeppelin.com/contracts/)
- [Hardhat Docs](https://hardhat.org/docs)

## Feedback
If this skill contains incorrect or outdated information, call:
agentrel_feedback(skill="ethereum/core", issue="<description>")