Skip to main content Implement NFT standards (ERC-721, ERC-1155) with proper metadata handling, minting strategies, and marketplace integration. Use when creating NFT contracts, building NFT marketplaces, or implementing digital asset systems.
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NFT Standards
Master ERC-721 and ERC-1155 NFT standards, metadata best practices, and advanced NFT features.
Do not use this skill when
The task is unrelated to nft standards
You need a different domain or tool outside this scope
Instructions
Clarify goals, constraints, and required inputs.
Apply relevant best practices and validate outcomes.
Provide actionable steps and verification.
If detailed examples are required, open resources/implementation-playbook.md.
Use this skill when
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);
}
}
ERC-1155 (Multi-Token Standard) // SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
contract GameItems is ERC1155, Ownable {
uint256 public constant SWORD = 1;
uint256 public constant SHIELD = 2;
uint256 public constant POTION = 3;
mapping(uint256 => uint256) public tokenSupply;
mapping(uint256 => uint256) public maxSupply;
constructor() ERC1155("ipfs://QmBaseHash/{id}.json") {
maxSupply[SWORD] = 1000;
maxSupply[SHIELD] = 500;
maxSupply[POTION] = 10000;
}
function mint(
address to,
uint256 id,
uint256 amount
) external onlyOwner {
require(tokenSupply[id] + amount <= maxSupply[id], "Exceeds max supply");
_mint(to, id, amount, "");
tokenSupply[id] += amount;
}
function mintBatch(
address to,
uint256[] memory ids,
uint256[] memory amounts
) external onlyOwner {
for (uint256 i = 0; i < ids.length; i++) {
require(tokenSupply[ids[i]] + amounts[i] <= maxSupply[ids[i]], "Exceeds max supply");
tokenSupply[ids[i]] += amounts[i];
}
_mintBatch(to, ids, amounts, "");
}
function burn(
address from,
uint256 id,
uint256 amount
) external {
require(from == msg.sender || isApprovedForAll(from, msg.sender), "Not authorized");
_burn(from, id, amount);
tokenSupply[id] -= amount;
}
}
Metadata Standards
Off-Chain Metadata (IPFS) {
"name": "NFT #1",
"description": "Description of the NFT",
"image": "ipfs://QmImageHash",
"attributes": [
{
"trait_type": "Background",
"value": "Blue"
},
{
"trait_type": "Rarity",
"value": "Legendary"
},
{
"trait_type": "Power",
"value": 95,
"display_type": "number",
"max_value": 100
}
]
}
On-Chain Metadata contract OnChainNFT is ERC721 {
struct Traits {
uint8 background;
uint8 body;
uint8 head;
uint8 rarity;
}
mapping(uint256 => Traits) public tokenTraits;
function tokenURI(uint256 tokenId) public view override returns (string memory) {
Traits memory traits = tokenTraits[tokenId];
string memory json = Base64.encode(
bytes(
string(
abi.encodePacked(
'{"name": "NFT #', Strings.toString(tokenId), '",',
'"description": "On-chain NFT",',
'"image": "data:image/svg+xml;base64,', generateSVG(traits), '",',
'"attributes": [',
'{"trait_type": "Background", "value": "', Strings.toString(traits.background), '"},',
'{"trait_type": "Rarity", "value": "', getRarityName(traits.rarity), '"}',
']}'
)
)
)
);
return string(abi.encodePacked("data:application/json;base64,", json));
}
function generateSVG(Traits memory traits) internal pure returns (string memory) {
// Generate SVG based on traits
return "...";
}
}
Royalties (EIP-2981) import "@openzeppelin/contracts/interfaces/IERC2981.sol";
contract NFTWithRoyalties is ERC721, IERC2981 {
address public royaltyRecipient;
uint96 public royaltyFee = 500; // 5%
constructor() ERC721("Royalty NFT", "RNFT") {
royaltyRecipient = msg.sender;
}
function royaltyInfo(uint256 tokenId, uint256 salePrice)
external
view
override
returns (address receiver, uint256 royaltyAmount)
{
return (royaltyRecipient, (salePrice * royaltyFee) / 10000);
}
function setRoyalty(address recipient, uint96 fee) external onlyOwner {
require(fee <= 1000, "Royalty fee too high"); // Max 10%
royaltyRecipient = recipient;
royaltyFee = fee;
}
function supportsInterface(bytes4 interfaceId)
public
view
override(ERC721, IERC165)
returns (bool)
{
return interfaceId == type(IERC2981).interfaceId ||
super.supportsInterface(interfaceId);
}
}
Soulbound Tokens (Non-Transferable) contract SoulboundToken is ERC721 {
constructor() ERC721("Soulbound", "SBT") {}
function _beforeTokenTransfer(
address from,
address to,
uint256 tokenId,
uint256 batchSize
) internal virtual override {
require(from == address(0) || to == address(0), "Token is soulbound");
super._beforeTokenTransfer(from, to, tokenId, batchSize);
}
function mint(address to) external {
uint256 tokenId = totalSupply() + 1;
_safeMint(to, tokenId);
}
// Burn is allowed (user can destroy their SBT)
function burn(uint256 tokenId) external {
require(ownerOf(tokenId) == msg.sender, "Not token owner");
_burn(tokenId);
}
}
Dynamic NFTs contract DynamicNFT is ERC721 {
struct TokenState {
uint256 level;
uint256 experience;
uint256 lastUpdated;
}
mapping(uint256 => TokenState) public tokenStates;
function gainExperience(uint256 tokenId, uint256 exp) external {
require(ownerOf(tokenId) == msg.sender, "Not token owner");
TokenState storage state = tokenStates[tokenId];
state.experience += exp;
// Level up logic
if (state.experience >= state.level * 100) {
state.level++;
}
state.lastUpdated = block.timestamp;
}
function tokenURI(uint256 tokenId) public view override returns (string memory) {
TokenState memory state = tokenStates[tokenId];
// Generate metadata based on current state
return generateMetadata(tokenId, state);
}
function generateMetadata(uint256 tokenId, TokenState memory state)
internal
pure
returns (string memory)
{
// Dynamic metadata generation
return "";
}
}
Gas-Optimized Minting (ERC721A) import "erc721a/contracts/ERC721A.sol";
contract OptimizedNFT is ERC721A {
uint256 public constant MAX_SUPPLY = 10000;
uint256 public constant MINT_PRICE = 0.05 ether;
constructor() ERC721A("Optimized NFT", "ONFT") {}
function mint(uint256 quantity) external payable {
require(_totalMinted() + quantity <= MAX_SUPPLY, "Exceeds max supply");
require(msg.value >= MINT_PRICE * quantity, "Insufficient payment");
_mint(msg.sender, quantity);
}
function _baseURI() internal pure override returns (string memory) {
return "ipfs://QmBaseHash/";
}
}
Resources
references/erc721.md : ERC-721 specification details
references/erc1155.md : ERC-1155 multi-token standard
references/metadata-standards.md : Metadata best practices
references/enumeration.md : Token enumeration patterns
assets/erc721-contract.sol : Production ERC-721 template
assets/erc1155-contract.sol : Production ERC-1155 template
assets/metadata-schema.json : Standard metadata format
assets/metadata-uploader.py : IPFS upload utility
Best Practices
Use OpenZeppelin : Battle-tested implementations
Pin Metadata : Use IPFS with pinning service
Implement Royalties : EIP-2981 for marketplace compatibility
Gas Optimization : Use ERC721A for batch minting
Reveal Mechanism : Placeholder → reveal pattern
Enumeration : Support walletOfOwner for marketplaces
Whitelist : Merkle trees for efficient whitelisting
Marketplace Integration
OpenSea: ERC-721/1155, metadata standards
LooksRare: Royalty enforcement
Rarible: Protocol fees, lazy minting
Blur: Gas-optimized trading
Limitations
Use this skill only when the task clearly matches the scope described above.
Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
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CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or multi-account), or reading/injecting/running secrets via op.
CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).