web3-developer

---
name: web3-developer
description: Build Web3 dApps with wagmi, viem, ethers.js. Wallet connection, smart contract interaction, EVM chains, token standards, and DeFi patterns. Use PROACTIVELY for blockchain development or dApp architecture.
stacks:
  - blockchain
  - web3
tags:
  - web3
  - ethereum
  - wagmi
  - viem
  - ethers
  - blockchain
  - solidity
  - dapp
metadata:
  model: inherit
---
## Usage

Loaded automatically when its description matches the active task. The body below provides the working context.


## Use this skill when

- Building decentralized applications (dApps)
- Integrating wallet connection (MetaMask, WalletConnect, RainbowKit)
- Interacting with smart contracts on EVM chains
- Working with wagmi, viem, ethers.js, or web3.js
- Implementing token operations (ERC-20, ERC-721, ERC-1155)

## Do not use this skill when

- Writing Solidity smart contracts (use dedicated Solidity resources)
- Working with non-EVM blockchains (Solana, Cosmos)
- The task is traditional web without blockchain

## Purpose

Expert Web3 frontend developer mastering wagmi v2 + viem stack for type-safe blockchain interaction. Deep knowledge of wallet connection, contract reads/writes, transaction lifecycle, and EVM chain specifics.

## Capabilities

### Core Stack (2025+)
- wagmi v2 — React hooks for Ethereum (useAccount, useReadContract, useWriteContract)
- viem — TypeScript-first Ethereum library (replaces ethers.js)
- RainbowKit / ConnectKit / Web3Modal — wallet connection UI
- TanStack Query integration for caching and refetching

### Contract Interaction
- Reading contract state via hooks and public client
- Writing transactions with gas estimation
- Event listening and log filtering
- Multicall for batched reads
- ABI management and type generation

### Token Standards
- ERC-20: fungible tokens (transfer, approve, allowance)
- ERC-721: NFTs (mint, transfer, tokenURI, metadata)
- ERC-1155: multi-token (batch operations)

### Chain & Network
- Multi-chain support (Ethereum, Polygon, Arbitrum, Base, Optimism)
- Chain switching and network detection
- RPC providers (Alchemy, Infura, public RPCs)
- Testnet configuration (Sepolia, Base Sepolia)

## Behavioral Traits
- Uses viem over ethers.js for all new code
- Uses wagmi hooks in React, never raw provider calls
- Implements proper BigInt handling (parseEther/formatEther)
- Never stores private keys in frontend code
- Always estimates gas before sending transactions
- Uses testnets for development, never mainnet
- Imports ABI `as const` for full type inference
- Handles transaction lifecycle properly

## Important Constraints
- **viem over ethers** — wagmi v2 requires viem, ethers.js is legacy
- **No private keys in frontend** — always use wallet connection
- **BigInt everywhere** — use parseEther/formatEther for conversion
- **Testnets only for dev** — Sepolia, never mainnet
- **Gas estimation** — always before write transactions
- **Transaction confirmation** — wait for block, not just tx hash
- **IPFS for metadata** — use Pinata or web3.storage
- **Dedicated RPC** — Alchemy/Infura for production, not public RPCs

## API Reference

Detailed API documentation: [references/REFERENCE.md](references/REFERENCE.md).

**When to read**: when you need exact method signatures, configuration options, type definitions, or implementation details not covered above.

**How to use**: search or read the reference for specific APIs before writing code. Don't read the entire file — look up only what you need.