🧩 DevNet-Only Developer Wallet Extension

A secure, open-source browser wallet for testing smart contracts across multiple blockchains — never mainnet.

🚀 Overview

DevNet Wallet is a lightweight, privacy-preserving Chrome/Brave extension that lets blockchain developers test and debug dApps on devnets and other test networks without risking real assets.

✨ Features

• ✅ Developer-only wallet – never stores or touches mainnet keys
• ✅ Supports both ECDSA (secp256k1) and Ed25519 (Solana) key types
• ✅ Ephemeral by default – private keys live in memory unless user encrypts
• ✅ Multi-chain testing – single UI for EVM and Solana testnets
• ✅ Extensible architecture – easy to add new testnets

Supported Networks

Network	Type	Chain/Cluster ID	RPC URL	Explorer	Faucet
Ethereum Sepolia	EVM	11155111	https://eth-sepolia.public.blastapi.io	sepolia.etherscan.io	sepoliafaucet.com
Polygon Amoy	EVM	80002	https://rpc-amoy.polygon.technology	amoy.polygonscan.com	faucet.polygon.technology
BSC Testnet	EVM	97	https://data-seed-prebsc-1-s1.binance.org:8545	testnet.bscscan.com	Binance Faucet
Avalanche Fuji	EVM	43113	https://api.avax-test.network/ext/bc/C/rpc	testnet.snowtrace.io	faucet.avax.network
Local Hardhat/Anvil	EVM	31337	http://127.0.0.1:8545	Local Dev	Built-in
Solana Devnet	Ed25519	devnet	https://api.devnet.solana.com	explorer.solana.com	faucet.solana.com

---

🧱 Architecture

Tech Stack

• Frontend: React + TypeScript + Tailwind CSS
• Blockchain Libraries:
  • ethers.js → EVM chains (secp256k1)
  • @solana/web3.js → Solana Devnet (Ed25519)
• Extension APIs: Manifest V3 (chrome.runtime, chrome.storage, chrome.action)
• Crypto:
  • EVM keys → BIP-39 / BIP-44 (HD wallets)
  • Solana keys → Ed25519 Keypair (tweetnacl)
• Storage: In-memory (default) or AES-encrypted sessionStorage

Project Structure

devnet-wallet/
├── manifest.json           # Extension manifest (V3)
├── package.json            # Dependencies
├── vite.config.ts          # Build configuration
├── tailwind.config.js      # Tailwind CSS config
├── tsconfig.json           # TypeScript config
├── index.html              # Popup HTML
├── public/
│   ├── icons/              # Extension icons
│   └── inject.js           # Injected wallet API
├── src/
│   ├── background/
│   │   └── index.ts        # Service worker
│   ├── content/
│   │   └── inject.ts       # Content script
│   ├── popup/
│   │   ├── index.tsx       # Popup entry
│   │   ├── Popup.tsx       # Main popup component
│   │   └── components/     # UI components
│   │       ├── Header.tsx
│   │       ├── CreateWalletView.tsx
│   │       ├── WalletView.tsx
│   │       └── SettingsView.tsx
│   ├── utils/
│   │   ├── evm.ts          # EVM wallet helpers
│   │   ├── solana.ts       # Solana key & tx helpers
│   │   ├── network.ts      # Network configurations
│   │   ├── faucet.ts       # Faucet integrations
│   │   ├── crypto.ts       # Encryption utilities
│   │   └── storage.ts      # Storage management
│   └── styles/
│       └── index.css       # Global styles
└── README.md

---

🧠 Core Features

🔐 Key Management

• Auto-generate new wallet on first load (ECDSA + Ed25519)
• Optional import (private key / seed phrase / Solana keypair)
• Optional encrypted export with "TESTNET ONLY" warning
• Auto-wipe keys on tab close
• Multi-format support:
  • 0x hex (private key – EVM)
  • Mnemonic (12/24 words)
  • Solana base58 secret key

🌍 Network Management

• Preloaded testnets (see table above)
• Manual switch dropdown
• Custom RPC addition with explicit "TESTNET ONLY" checkbox
• Auto-reject chainId 1 (mainnet) or Solana mainnet-beta

💸 Faucet Access

• Per-network "Get Test Tokens" button
• Built-in local faucet for Hardhat/Anvil
• Direct links to external faucets

🧾 Transactions & Signing

• Transaction preview modal (from/to/value/gas/data)
• EVM: ethers.Wallet.signTransaction & sendTransaction
• Solana: Transaction via @solana/web3.js
• Logs all signed tx hashes for developer debugging

💬 UI Overview

Popup Panel

• Network selector
• Wallet address (copy icon)
• Balance display
• Buttons: Send / Receive / Faucet / Settings

Settings Panel

• "Persist key (encrypted)" toggle
• Manage networks
• Clear wallet
• Export key (with warning)
• Debug logs toggle

Visual Safety

• Red banner: "TESTNET ONLY – NO REAL FUNDS"
• Always display chain name and RPC URL in header

---

🧰 Developer Integration

Injected APIs

The extension injects window.devnetWallet (EVM) and window.solanaDevnetWallet (Solana) into web pages. Legacy aliases (window.testnetWallet, window.solanaTestnetWallet) remain available for compatibility.

EVM API (similar to window.ethereum)

// Request accounts
const accounts = await window.devnetWallet.request({ 
  method: 'eth_requestAccounts' 
});

// Get current chain
const chainId = await window.devnetWallet.request({ 
  method: 'eth_chainId' 
});

// Send transaction
const txHash = await window.devnetWallet.request({
  method: 'eth_sendTransaction',
  params: [{
    from: accounts[0],
    to: '0x...',
    value: '0x...',
    gas: '0x...',
  }]
});

// Listen for network changes
window.devnetWallet.on('chainChanged', (chainId) => {
  console.log('Network changed to:', chainId);
});

Solana API (similar to Phantom)

// Connect wallet
const { publicKey } = await window.solanaDevnetWallet.connect();

// Send transaction
const connection = new solanaWeb3.Connection('https://api.devnet.solana.com');
const transaction = new solanaWeb3.Transaction().add(
  solanaWeb3.SystemProgram.transfer({
    fromPubkey: publicKey,
    toPubkey: recipientPublicKey,
    lamports: amount,
  })
);

const { signature } = await window.solanaDevnetWallet.signAndSendTransaction(transaction);

---

🛡️ Security Model

• ✅ Handshake-authenticated messaging bridge between dApp, content script, and service worker
• ✅ Strict RPC input validation before forwarding any call to external providers
• ✅ Block chainId 1 and mainnet-beta
• ✅ Keys never leave local context
• ✅ All RPC calls HTTPS or localhost
• ✅ No analytics or telemetry
• ✅ Strong warnings for seed import/export
• ✅ UI must show active network and testnet badge at all times

---

🔧 Build & Run

Prerequisites

• Node.js 18+ and npm/yarn
• Chrome or Brave browser

Installation

# Clone the repository
git clone https://github.com/yourname/devnet-wallet
cd devnet-wallet

# Install dependencies
npm install

# Build the extension
npm run build

Load in Browser

1. Open Chrome/Brave
2. Navigate to chrome://extensions/
3. Enable Developer mode
4. Click Load unpacked
5. Select the build/ directory

Development Mode

# Run in watch mode
npm run dev

---

💡 Example User Flow

1. Developer installs extension
2. On launch, wallet auto-generates EVM & Solana keys (in memory)
3. Developer selects "Sepolia" or "Solana Devnet"
4. Clicks Get Test Tokens to fund wallet
5. Deploys contracts or runs CI tests
6. Closes browser → keys wiped

---

🎨 Design Guidelines

• Tailwind CSS + Inter font
• Developer-centric dark theme
• Rounded corners (2xl), soft shadows, large padding
• Animated banner "TESTNET ONLY"

---

🧩 Future Extensions

• Add Base Goerli, Linea, zkSync Testnet
• Multi-account management
• Built-in Solana airdrops button
• Local node manager (start/stop Anvil)
• Web dashboard for testnet analytics

---

📜 License

MIT – Open source for educational / developer testing purposes.

---

⚠️ Disclaimer

Never use with mainnet funds. This wallet is for testnets only.

This extension is designed exclusively for development and testing purposes. It includes safeguards to prevent mainnet usage, but developers should always exercise caution.

---

🤝 Contributing

Contributions are welcome! Please open an issue or submit a pull request.

Development Setup

npm install
npm run dev      # Development mode
npm run build    # Production build

---

🧪 Testing with Smart Contracts

The contracts/ directory contains sample smart contracts to test the wallet's functionality:

Quick Start with Contracts

cd contracts
npm install
npm run compile

# Start local Hardhat node
npm run node

# Deploy contracts (in another terminal)
npm run deploy:local

Available Contracts

1. SimpleStorage - Test basic transactions and state changes
2. TestToken - ERC20 token for testing transfers
3. Guestbook - Test string parameters and events

See contracts/README.md for detailed instructions.

---

� Developer Tools

Generate Solana Keypair (JSON Format)

From the extension UI:

1. Open the wallet popup → Settings.
2. Under Export Keys, click Show Private Keys.
3. Press Download Solana Keypair (.json).

The browser downloads solana-wallet-keypair.json containing the Uint8Array representation that Solana CLI, Solana Playground, and other tools expect.

Prefer the command line? You can still run:

node scripts/generate-keypair.js YOUR_BASE64_SECRET_KEY

📖 See docs/SOLANA_DEPLOY_GUIDE.md for full deployment guide.

---

�📚 Documentation

Key Code Snippets

EVM Ephemeral Wallet

import { ethers } from "ethers";

export async function createEvmWallet(rpcUrl: string) {
  const provider = new ethers.providers.JsonRpcProvider(rpcUrl);
  const net = await provider.getNetwork();
  
  if (net.chainId === 1) throw new Error("Mainnet not allowed");
  
  return ethers.Wallet.createRandom().connect(provider);
}

Solana Ephemeral Wallet

import { Keypair, Connection } from "@solana/web3.js";

export function createSolanaWallet(cluster = "https://api.devnet.solana.com") {
  const connection = new Connection(cluster, "confirmed");
  const wallet = Keypair.generate();
  return { wallet, connection };
}

Prevent Mainnet

const BLOCKED = [1, 137, 56]; // Ethereum, Polygon, BSC mainnets

if (BLOCKED.includes(chainId) || cluster === "mainnet-beta") {
  throw new Error("Mainnet not supported");
}

---

🙏 Acknowledgments

Built with ❤️ for the blockchain developer community.

---

Made for testing. Built for developers. Never for mainnet.