View All NFTs Owned by a Specific Ethereum Wallet – Methods and Tools

In order to get all NFTs of a user, you need to have an indexed database where you save this data. Then you index all Transfer events of ERC721 contracts and eventually calculate the balances for every address and save this into a database where it's quickly accessible for every request. The transfer events to index for ERC721 is the following:

Transfer(address,address,uint256)

It's a pretty cumbersome process, and unfortunately, nothing that is available with a simple web3.js call. This has to do with the way data is structured in the blockchain, which just contains transactions and not actual indexed user data.

If you're looking for an easy way to get NFT balances of users with a simple call, you can use the service I built, moralis.io. We built it because I had the exact same issue you have. It's completely free to use.

• /{WALLET_ADDRESS]/nft - get all NFTs owned by address
• /nft/{CONTRACT_ADDRESS}/owners - get all owners of a specific NFT contract
• /nft/{CONTRACT_ADDRESS}/{TOKEN_ID}/owners - get all owners of a specific NFT contract and ID

Or you can use the moralis sdk and you can use the frontend JavaScript functions.

//get NFTs for current user on ETH Mainnet
const userEthNFTs = await Moralis.Web3API.account.getNFTs();

//get all owners of specific NFTS
const options = { address: "0xd...07", chain: "bsc" };
const nftOwners = await Moralis.Web3API.token.getNFTOwners(options);

Full disclosure, I work at moralis.

Because the standard says so.

https://eips.ethereum.org/EIPS/eip-721

/// @dev This emits when ownership of any NFT changes by any mechanism.
///  This event emits when NFTs are created (`from` == 0) and destroyed
///  (`to` == 0). Exception: during contract creation, any number of NFTs
///  may be created and assigned without emitting Transfer. At the time of
///  any transfer, the approved address for that NFT (if any) is reset to none.
event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);