Web3 & DApp Development Fundamentals · Lesson

Minting NFTs

Unique token IDs.

Minting NFTs is a free Web3 & DApp Development Fundamentals lesson on CoddyKit. This is lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Web3 & DApp Development Fundamentals learning path, and your progress syncs across the web and the CoddyKit app. The Web3 & DApp Development Fundamentals course includes 4 lessons in total.

Creating Unique Tokens

Minting an NFT creates a brand new token with a unique tokenId and assigns it an owner. Unlike ERC-20 minting (which adds to a balance), each NFT mint produces a distinct, identifiable asset.

Ownership Mapping

The core NFT state is a mapping from tokenId to owner address, plus a balance count per owner.

<code>mapping(uint256 => address) private _owners;
mapping(address => uint256) private _balances;</code>

A Basic Mint Function

Minting assigns the token to a recipient, increments their balance, and emits a Transfer from the zero address - just like ERC-20 mint conventions.

<code>function _mint(address to, uint256 tokenId) internal {
    require(to != address(0), 'mint to zero');
    require(_owners[tokenId] == address(0), 'already minted');
    _owners[tokenId] = to;
    _balances[to] += 1;
    emit Transfer(address(0), to, tokenId);
}</code>

Preventing Duplicate IDs

A token id can only be minted once. The check _owners[tokenId] == address(0) ensures you never overwrite an existing token.

<code>require(_owners[tokenId] == address(0), 'token already exists');</code>

Auto-Incrementing IDs

To avoid id collisions, many contracts use a counter that increases with each mint, guaranteeing unique sequential ids.

<code>uint256 private _nextId;

function mint(address to) public {
    uint256 id = _nextId;
    _nextId += 1;
    _mint(to, id);
}</code>

Safe Minting

_safeMint behaves like _mint but, if the recipient is a contract, verifies it implements onERC721Received. This prevents NFTs from being locked in contracts that cannot handle them.

<code>function _safeMint(address to, uint256 tokenId) internal {
    _mint(to, tokenId);
    require(_checkOnERC721Received(to, tokenId), 'unsafe recipient');
}</code>

Access Control

Like ERC-20, an unrestricted mint is dangerous. Gate minting behind ownership or a minter role so only authorized accounts can create tokens.

<code>function mint(address to, uint256 id) public onlyOwner {
    _safeMint(to, id);
}</code>

Public Mint with Payment

Many NFT drops let the public mint by paying a fee. The function is payable and checks the sent value.

<code>uint256 public price = 0.05 ether;

function publicMint() public payable {
    require(msg.value >= price, 'insufficient payment');
    _safeMint(msg.sender, _nextId);
    _nextId += 1;
}</code>

Setting Metadata at Mint

When minting you often record a per-token metadata URI so each NFT can have its own image and attributes.

<code>mapping(uint256 => string) private _tokenURIs;

function mintWithURI(address to, uint256 id, string memory uri) public onlyOwner {
    _safeMint(to, id);
    _tokenURIs[id] = uri;
}</code>

Supply Limits

Collections usually cap the total number of NFTs. Enforce it with a max-supply check during minting.

<code>uint256 public constant MAX_SUPPLY = 10000;

function mint(address to) public onlyOwner {
    require(_nextId < MAX_SUPPLY, 'sold out');
    _safeMint(to, _nextId);
    _nextId += 1;
}</code>

Batch Minting

To mint several NFTs in one transaction, loop the mint logic. Be mindful of the block gas limit for large batches.

<code>function batchMint(address to, uint256 count) public onlyOwner {
    for (uint256 i = 0; i < count; i++) {
        _safeMint(to, _nextId);
        _nextId += 1;
    }
}</code>

Quick Check

Test your understanding of minting NFTs.

Recap

You learned how to mint NFTs:

Each mint assigns a unique tokenId to an owner and emits Transfer from address(0)
Prevent duplicate ids; auto-increment counters keep ids unique
_safeMint protects against locking NFTs in incompatible contracts
Add access control, optional payment, metadata, supply caps, and batch minting

Frequently Asked Questions

Is the “Minting NFTs” lesson free?

Yes — the full text of “Minting NFTs” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Web3 & DApp Development Fundamentals course, upgrade to CoddyKit PRO. The Web3 & DApp Development Fundamentals course includes 4 lessons in total.

What will I learn in “Minting NFTs”?

Unique token IDs. You practise Web3 & DApp Development Fundamentals with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Web3 & DApp Development Fundamentals?

No prior experience is required. Web3 & DApp Development Fundamentals on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 2 of 4.

How long does the “Minting NFTs” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Web3 & DApp Development Fundamentals lesson?

Yes. Every Web3 & DApp Development Fundamentals lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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