guides

Introduction

EIP-6551 enhances the features of NFTs (ERC-721 tokens) by giving each token its own smart contract account, also known as token-bound accounts (TBA). These smart contract accounts equip NFTs with the ability to operate like traditional blockchain wallets, allowing state changes and features such as holding ERC-20 tokens, other NFTs, and ether. Programmable accounts open up a myriad of use cases, limited only by the developer’s imagination and the protocol’s constraints.

Importantly, EIP-6551 is backwards compatible and doesn’t mandate custom logic within the NFT smart contract. This compatibility allows NFT projects that were created before the introduction of EIP-6551 to adopt smart contract accounts via a permissionless registry.

Use cases for token bound accounts:

• Gaming - A character, represented as an NFT, can possess its own inventory (like weapons, gold, etc.) using a smart wallet
• Investing - Utilize NFTs and their smart contract accounts to organize assets and sell entire investment portfolios in a single transaction
• Social (DAOs) - NFTs representing DAO membership can now maintain their own transaction history

Create an NFT with a Token Bound Account

This guide demonstrates how to create and interact with three smart contracts:

1. An ERC-721 smart contract that serves as our NFT.
2. A registry contract that deploys smart contract account associated with a given ERC-721 and computes the token bound account address.
3. A token bound account contract that can send and receive ether and other ERC-20 tokens.

Tools

We will use a few tools to write and deploy our smart contracts:

Tool	Description
Hardhat	Helps deploy and interact with smart contracts
Node.js	Developer environment
OpenZeppelin	An open library for building secure smart contracts
Coinbase Wallet	Non-custodial wallet for creating accounts and interacting with the blockchain

Getting started

We will be deploying these smart contracts on the Base Goerli testnet allowing us to see transaction information on BaseScan.

Using a testnet requires us to obtain testnet funds from a faucet to deploy and interact with our smart contracts on that network.

Configure Coinbase Wallet for testnet interactions

Warning: This demo requires the use of private keys in order to effectively interact with the blockchain. For this demo, use newly created wallets as a safety measure.

Depending on system settings your wallet may look different

Open the Coinbase Wallet browser extension then click on the Settings tab

Select “Developer Settings”

Toggle “Testnets” on

Request Testnet Funds

Click on the Settings tab

Select “Networks”

Select “Testnets” tab

Click on the water (💧) icon

Request testnet funds

Alternatively, use the base faucet

Environment Setup

Clone this repo

git clone https://github.com/base-org/guides.git

Change into the directory

cd base-guides/6551

Initiate a node project and install dependencies:

The dependencies in this project are as follows:

Dependencies	Description
hardhat	Helps deploy and interact with smart contracts
hardhat-toolbox	Bundles all the commonly used packages and Hardhat plugins we recommend to start developing with Hardhat.
dot-env	Dotenv is a zero-dependency module that loads environment variables from a .env file into process.env
openzeppelin/contracts	A library for secure smart contract development.

Install them by running:

npm install

Wallet setup

Assuming you have set up your wallet (and safely stored away your seed phrase) and have some funds (testnet or mainnet), obtain the addresses and private keys needed for the demo.

Copy your private key

Do not share your private key with anyone.

Click on the Settings tab

Select “Developer Settings”

Click on “Show private key”

Enter password

Read disclaimer to copy address

Type the following command into your terminal application:

export WALLET_KEY=

Paste the private key after export WALLET_KEY= within your terminal

Your terminal should look like this

export WALLET_KEY=0xde9be858da4a475276426320d5e9262ecfc3ba460bfac56360bfa6c4c28b4ee0

Press enter/return on your keyboard to save the value

Verify your private key has been saved:

echo $WALLET_KEY

Sample output:

0xde9be858da4a475276426320d5e9262ecfc3ba460bfac56360bfa6c4c28b4ee0

Obtain details of another account

Note: Each account will need funds in order to deploy contracts and interact with Base.

From the assets tab, click on the current address/account

Select another wallet/account

If you do not have an additional account click the “Add & manage wallets” button to create a new account.

Copy the address of the newly selected account

Type the following command into your terminal application

Your terminal should look like this:

export WALLET2_ADDR=

Paste the address as an environment variable within your terminal

export WALLET2_ADDR=0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266

Press enter/return on your keyboard to save the value

Verify the account address has been saved:

echo $WALLET2_ADDR

Sample output:

0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266

Save the private key of the currently selected account

Each account has its own private key.

This wallet will be the original owner of the NFT minted later in this tutorial. You will need the private key of the currently selected wallet in order to transfer the ownership of the NFT.

Refer to the previous steps for obtaining and copying your private keys and save them as an environment variable WALLET2_KEY using your terminal.

Example:

export WALLET2_KEY=0x5de4111afa1a4b94908f83103eb1f1706367c2e68ca870fc3fb9a804cdab365a

Verify your private key has been saved:

echo $WALLET2_KEY

Sample output:

0x5de4111afa1a4b94908f83103eb1f1706367c2e68ca870fc3fb9a804cdab365a

Deploy contracts on the Base testnet

The following script will deploy three smart contracts and save their deployment information in a file called deploymentData.json.

Once you become comfortable deploying contracts on a testnet, you may deploy contracts on the Base mainnet by replacing --network base-goerli with --network base-mainnet .

npx hardhat run scripts/01_deploy_contracts.js --network base-goerli

Sample output:

ERC-721 Contract deployed at: 0xECD4b1C01a0aF70C7Ee985db389E294D01DffEC0
Saved deployment data to a new file: deploymentData.json
Deployed registry contract at: 0x58B2EAe6f05abf9C1e1566AD9307C67B41627A1e

[
  {
  NftContract: {
  address: '0xECD4b1C01a0aF70C7Ee985db389E294D01DffEC0',
  deployer: '0xB6d00D83158feE6695C72ff9c5E915478A465724',
  deploymentHash: '0xedacc11c5268b155a9a6918b5e1cc19031343f41519f596eb264ef6ca3feaeb4'
  }
  },
  {
  ERC6551Registry: {
  address: '0x58B2EAe6f05abf9C1e1566AD9307C67B41627A1e',
  deployer: '0xB6d00D83158feE6695C72ff9c5E915478A465724',
  deploymentHash: '0xcf45022f97e682eccc87c903c6eff38ba2c080aeb69c69da4662914aacf4f481'
  }
  }
]

  Deployment data saved to: deploymentData.json
  Deploying Token Bound Account
  Token bound account deployed at: 0xdAcaEDF79Fa33405446F2B9Fbf820Cef84507f22

[
  {
    NftContract: {
    address: '0xECD4b1C01a0aF70C7Ee985db389E294D01DffEC0',
    deployer: '0xB6d00D83158feE6695C72ff9c5E915478A465724',
    deploymentHash: '0xedacc11c5268b155a9a6918b5e1cc19031343f41519f596eb264ef6ca3feaeb4'
    }
  },
  {
    ERC6551Registry: {
    address: '0x58B2EAe6f05abf9C1e1566AD9307C67B41627A1e',
    deployer: '0xB6d00D83158feE6695C72ff9c5E915478A465724',
    deploymentHash: '0xcf45022f97e682eccc87c903c6eff38ba2c080aeb69c69da4662914aacf4f481'
    }
  },
    {
    ERC6551Account: {
    address: '0xdAcaEDF79Fa33405446F2B9Fbf820Cef84507f22',
    deployer: '0xB6d00D83158feE6695C72ff9c5E915478A465724',
    deploymentHash: '0xbfe9ab08951e07660c2d3a6e9b16e6e959a174530f1e28aba9c98a19c381f586'
    }
  }
]

Deployment data saved to: deploymentData.json

This script will mint an NFT and assign its ownership to the WALLET2_ADDR account

npx hardhat run scripts/02_mint_nft.js --network --network base-goerli

Sample output:

0xECD4b1C01a0aF70C7Ee985db389E294D01DffEC0
Minting NFT...
TokenId 0 is owned by address: 0x9eEd71442F60440b39Def927047e5823c0b208D4

This script will create and compute the address for a smart contract wallet (token bound account)

npx hardhat run scripts/03_create_account.js --network base-goerli

Sample output:

Computed Address: 0xA5153E5D9A384e519fEa64D228797edb4a448d45

This script will send funds from WALLET_KEY to the token bound account and transfer ownership of the NFT from WALLET2_ADDR to WALLET_KEY.

npx hardhat run scripts/04_account_interaction.js --network base-goerli

Sample output:

Current owner of tokenId 0 is 0x9eEd71442F60440b39Def927047e5823c0b208D4
Token account has 0 ETH
New owner of tokenId 0 is 0xB6d00D83158feE6695C72ff9c5E915478A465724
Token account has 12500000000000000 ETH

Congrats!

Clear the private keys from your environment variables by running this command:

export WALLET_KEY=nil
export WALLET2_KEY=nil

This site is open source. Improve this page.