ERC-6551 Token-Bound Accounts

What Token-Bound Accounts Do

Normally, NFTs are owned by user accounts. ERC-6551 inverts this: each NFT itself can own a smart contract wallet. So your Bored Ape NFT can have its own ETH balance, hold other tokens, hold other NFTs, even execute transactions. When you transfer the Ape, the wallet's contents transfer with it. The standard was finalised in 2023 and has been adopted by several major projects.

Use Cases That Make Sense

The clearest use case: in-game characters with inventories. Your character NFT owns a wallet containing weapons NFTs, gold tokens, and quest items. Sell the character, and the inventory goes with it as a single bundled transfer. Another use case: NFT-as-membership where the NFT's wallet holds accrued reputation tokens. Another: 'composable' NFTs where a parent NFT contains other NFTs that affect its display.

How the Mechanism Works

ERC-6551 defines a 'registry' contract that deterministically computes the address of any NFT's token-bound account. Anyone can deploy the actual wallet contract for any NFT (it's permissionless), and the wallet address is predictable from the NFT's contract + token ID. The wallet itself implements ERC-6551's account interface — it has an `execute()` function that the NFT's current owner can call to operate the wallet.

• Each NFT can have its own wallet that holds other assets
• Transfer the NFT → the wallet and its contents transfer too
• Registry contract computes wallet addresses deterministically
• Wallet logic is permissionless — anyone can deploy the wallet for any NFT