Web3 & DApp Development Fundamentals · Lesson

Minting NFTs

Unique token IDs.

Minting NFTs is a free Web3 & DApp Development Fundamentals lesson on CoddyKit — 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, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

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, and the Web3 & DApp Development Fundamentals course includes 4 lessons in total. 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.

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; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.

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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