interface ERC721 {

    event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);
    event Approval(address indexed _owner, address indexed _approved, uint256 indexed _tokenId);
    event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
    function balanceOf(address _owner) external view returns (uint256);
    function ownerOf(uint256 _tokenId) external view returns (address);
    function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
    function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;
    function transferFrom(address _from, address _to, uint256 _tokenId) external payable;
    function approve(address _approved, uint256 _tokenId) external payable;
    function setApprovalForAll(address _operator, bool _approved) external;
    function getApproved(uint256 _tokenId) external view returns (address);
    function isApprovedForAll(address _owner, address _operator) external view returns (bool);
}

interface ERC165 {
    function supportsInterface(bytes4 interfaceID) external view returns (bool);
}

interface ERC721TokenReceiver {
    function onERC721Received(address _operator, address _from, uint256 _tokenId, bytes _data) external returns(bytes4);
}			
			
			

可選實現介面，ERC721Metadata 介面用於提供合約的元數據：name , symbol 及 URI（NFT所對應的資源）。

			
其介面定義如下：

interface ERC721Metadata /* is ERC721 */ {
    function name() external pure returns (string _name);
    function symbol() external pure returns (string _symbol);
    function tokenURI(uint256 _tokenId) external view returns (string);
}

介面說明：
name(): 返回合約名字，儘管是可選，但強烈建議實現，即便是返回空字元串。
symbol(): 返回合約代幣符號，儘管是可選，但強烈建議實現，即便是返回空字元串。
tokenURI(): 返回_tokenId所對應的外部資源檔案的URI（通常是IPFS或HTTP(S)路徑）。外部資源檔案需要包含名字、描述、圖片，其格式的要求如下：			
			
			

可選實現介面，ERC721Enumerable的主要目的是提高合約中NTF的可訪問性，其介面定義如下：

			
interface ERC721Enumerable /* is ERC721 */ {
    function totalSupply() external view returns (uint256);
    function tokenByIndex(uint256 _index) external view returns (uint256);
    function tokenOfOwnerByIndex(address _owner, uint256 _index) external view returns (uint256);
}
介面說明：

totalSupply(): 返回NFT總量
tokenByIndex(): 通過索引返回對應的tokenId。
tokenOfOwnerByIndex(): 所有者可以一次擁有多個的NFT, 此函數返回_owner擁有的NFT列表中對應索引的tokenId。