NFT Development Skill

Master NFT development with token standards, metadata design, marketplace integration, and on-chain generative art.

Quick Start

# Invoke this skill for NFT development
Skill("nft-development", topic="standards", standard="ERC721A")

Topics Covered

1. Token Standards

Choose the right standard:

• ERC-721: Standard NFTs, one token per ID
• ERC-721A: Gas-optimized batch minting
• ERC-1155: Multi-token, semi-fungible
• DN404: Divisible NFT hybrid

2. Metadata Design

Structure your NFT data:

• On-chain: Base64 JSON, SVG
• IPFS: Content-addressed storage
• Arweave: Permanent storage
• Dynamic: Evolving traits

3. Marketplace Integration

List and sell NFTs:

• OpenSea: Seaport protocol
• Royalties: EIP-2981
• Operator Filter: Royalty enforcement
• Collection Verification: Metadata standards

4. On-Chain Art

Generate art in Solidity:

• SVG Generation: Dynamic shapes
• Seed-based: Deterministic randomness
• Traits: Rarity distribution
• Base64: Data URI encoding

Code Examples

ERC-721A Mint

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "erc721a/contracts/ERC721A.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract MyNFT is ERC721A, Ownable {
    uint256 public constant MAX_SUPPLY = 10000;
    uint256 public constant PRICE = 0.08 ether;

    error MaxSupplyReached();
    error InsufficientPayment();

    constructor() ERC721A("MyNFT", "MNFT") Ownable(msg.sender) {}

    function mint(uint256 quantity) external payable {
        if (_totalMinted() + quantity > MAX_SUPPLY) revert MaxSupplyReached();
        if (msg.value < PRICE * quantity) revert InsufficientPayment();

        _mint(msg.sender, quantity);
    }

    function _startTokenId() internal pure override returns (uint256) {
        return 1;
    }
}

On-Chain SVG

function tokenURI(uint256 tokenId) public view returns (string memory) {
    uint256 seed = seeds[tokenId];

    string memory svg = string(abi.encodePacked(
        '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 400 400">',
        '<rect width="400" height="400" fill="#', _getColor(seed), '"/>',
        '<circle cx="200" cy="200" r="80" fill="#', _getColor(seed >> 24), '"/>',
        '</svg>'
    ));

    string memory json = string(abi.encodePacked(
        '{"name":"Art #', tokenId.toString(),
        '","image":"data:image/svg+xml;base64,', Base64.encode(bytes(svg)), '"}'
    ));

    return string(abi.encodePacked(
        "data:application/json;base64,",
        Base64.encode(bytes(json))
    ));
}

EIP-2981 Royalties

import "@openzeppelin/contracts/token/common/ERC2981.sol";

contract NFTWithRoyalty is ERC721A, ERC2981 {
    constructor() {
        _setDefaultRoyalty(msg.sender, 500); // 5%
    }

    function supportsInterface(bytes4 interfaceId)
        public view override(ERC721A, ERC2981)
        returns (bool)
    {
        return super.supportsInterface(interfaceId);
    }
}

Metadata Schema

ERC-721 Standard

{
  "name": "Cool NFT #1",
  "description": "A very cool NFT",
  "image": "ipfs://QmXxx.../1.png",
  "animation_url": "ipfs://QmXxx.../1.mp4",
  "external_url": "https://example.com/1",
  "attributes": [
    { "trait_type": "Background", "value": "Blue" },
    { "trait_type": "Rarity", "value": "Legendary" },
    { "display_type": "number", "trait_type": "Power", "value": 100 }
  ]
}

Standard Comparison

Common Pitfalls

Troubleshooting

"Metadata not showing on OpenSea"

1. Verify tokenURI returns valid JSON
2. Check IPFS gateway accessibility
3. Refresh metadata via API:

curl "https://api.opensea.io/api/v2/chain/ethereum/contract/{addr}/nfts/{id}/refresh"

"Batch mint out of gas"

• Use ERC-721A instead of ERC-721
• Limit batch size to 10-20 per tx

"Royalties not enforced"

Implement operator filter:

import "operator-filter-registry/src/DefaultOperatorFilterer.sol";

function setApprovalForAll(address op, bool approved)
    public override onlyAllowedOperatorApproval(op)
{
    super.setApprovalForAll(op, approved);
}

Gas Optimization

Cross-References

• Bonded Agent: 07-nft-development
• Related Skills: solidity-development, web3-frontend

Resources

• ERC-721: eips.ethereum.org/EIPS/eip-721
• ERC-721A: erc721a.org
• OpenSea Metadata: docs.opensea.io/docs/metadata-standards

Version History