NFT Standards

Master ERC-721 and ERC-1155 NFT standards, metadata best practices, and advanced NFT features.

When to Use This Skill

• Creating NFT collections (art, gaming, collectibles)
• Implementing marketplace functionality
• Building on-chain or off-chain metadata
• Creating soulbound tokens (non-transferable)
• Implementing royalties and revenue sharing
• Developing dynamic/evolving NFTs

ERC-721 (Non-Fungible Token Standard)

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract MyNFT is ERC721URIStorage, ERC721Enumerable, Ownable {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;

    uint256 public constant MAX_SUPPLY = 10000;
    uint256 public constant MINT_PRICE = 0.08 ether;
    uint256 public constant MAX_PER_MINT = 20;

    constructor() ERC721("MyNFT", "MNFT") {}

    function mint(uint256 quantity) external payable {
        require(quantity > 0 && quantity <= MAX_PER_MINT, "Invalid quantity");
        require(_tokenIds.current() + quantity <= MAX_SUPPLY, "Exceeds max supply");
        require(msg.value >= MINT_PRICE * quantity, "Insufficient payment");

        for (uint256 i = 0; i < quantity; i++) {
            _tokenIds.increment();
            uint256 newTokenId = _tokenIds.current();
            _safeMint(msg.sender, newTokenId);
            _setTokenURI(newTokenId, generateTokenURI(newTokenId));
        }
    }

    function generateTokenURI(uint256 tokenId) internal pure returns (string memory) {
        // Return IPFS URI or on-chain metadata
        return string(abi.encodePacked("ipfs://QmHash/", Strings.toString(tokenId), ".json"));
    }

    // Required overrides
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId,
        uint256 batchSize
    ) internal override(ERC721, ERC721Enumerable) {
        super._beforeTokenTransfer(from, to, tokenId, batchSize);
    }

    function _burn(uint256 tokenId) internal override(ERC721, ERC721URIStorage) {
        super._burn(tokenId);
    }

    function tokenURI(uint256 tokenId) public view override(ERC721, ERC721URIStorage) returns (string memory) {
        return super.tokenURI(tokenId);
    }

    function supportsInterface(bytes4 interfaceId)
        public
        view
        override(ERC721, ERC721Enumerable)
        returns (bool)
    {
        return super.supportsInterface(interfaceId);
    }

    function withdraw() external onlyOwner {
        payable(owner()).transfer(address(this).balance);
    }
}