🐾 CryptoPets Backend

A Node.js + Express backend to interact with the CryptoPets smart contract deployed on Ethereum (e.g., Sepolia testnet). This has been developed to interact wiht the CrypoPets smart contract, which source code is available here. The contract to which this backend connects is deployed here.

🧑🏽‍⚕️ Testing options

Option 1

1. Deploy your own CryptoPets NFT contract by following the instructions on this link.
2. Run your server locally to interact with the deployed smart contract.

Option 2

1. Interact with the already deployed smart contract, which address you can find on this link.

🚀 Features

• Mint new NFT pets
• Fetch pet information
• Update pet name and age
• Vote for the cutest pet
• Retrieve the winning pets
• Get the tokenURI

📦 Requirements

• Node.js v18 or higher
• NPM or Yarn
• A deployed smart contract and its ABI
• .env file with credentials (see below)

🔧 Installation

Clone the repository:

git clone https://github.com/your-username/cryptopets-backend.git
cd cryptopets-backend

Install dependencies:

npm install

🛠️ Configuration

Part 1

You are going to need an address for this server to sign the transactions and pay for the gas. If you don't want to use your own address (recommended), use the generateAndFundWallet.js script:

1. Install dependencies

npm install express ethers dotenv cors

2. Include the private key of the wallet from which you want to fund the server's wallet at a new .env file

SENDER_PRIVATE_KEY=<wallet_with_funds_private_key>
RPC_URL=https://sepolia.infura.io/v3/<your_infura_project_id>

3. Adjust the amount of ETH you want to send to the new wallet in this line:

const amountToSend = "0.0000001"; // Adjust amount if needed

4. Run the script:

node generateAndFundWallet.js

This will return a wallet address and a private key that wil be set automatically in your .env file, overriding the previous sensitive data. Something similar to this should appear in the new file:

PRIVATE_KEY=4b8b5.........3edf4
WALLET_ADDRESS=0x91101.........187
MNEMONIC="behind boat check fade abuse chef squirrel inner capital dog model occur"

⚠️ Never share your private key. This wallet should only be used by the backend and should not store significant funds.

Part 2

Add to the .env file the address of the CryptoPets smart contract and the port:

CONTRACT_ADDRESS=0xYourContractAddressHere // You can use mine, as mentioned above in Testing Option 2, or yours (Option 1)
PORT:3000 // you can use any

▶️ Running the server

Start the server with:

node cryptopet-backend.js

The backend will be available at: http://localhost:3000

🧠 Notes

• Interactions with the blockchain (e.g., minting, voting) may take a few seconds.
• This backend uses a dedicated wallet to sign transactions.
• Any BigInt values are converted to strings before being returned in JSON.

📄 License

MIT License

👨🏽‍💻 Author

Developed by Guillermo Pastor gpastor.kuster@gmail.com