NFTs on Sui: A Developer’s Guide to Building, Minting, and Managing Digital Assets

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Non-fungible tokens (NFTs) have evolved from digital collectibles into powerful tools for representing ownership of art, in-game items, event tickets, and more. On the Sui blockchain, NFTs are not just static assets—they're dynamic, composable, and built with performance and scalability in mind. This guide explores how developers can create, manage, and enhance NFTs on Sui using Move smart contracts, off-chain storage, wallet integrations, and advanced features like upgradable and rentable NFTs.

Understanding NFTs on Sui

An NFT on Sui is a unique digital object with a distinct identifier (object ID) that ensures its non-fungibility. Unlike fungible tokens such as SUI coin, each NFT represents a one-of-a-kind asset. These tokens can be owned by user accounts or even other objects—enabling complex ownership hierarchies. For example, a game character (itself an NFT) might own a weapon NFT, creating rich, nested digital ecosystems.

NFTs on Sui are created and managed through Move smart contracts, which define rules for minting, transferring, upgrading, and displaying assets. The flexibility of Move allows developers to implement custom logic tailored to their application—whether it’s a game, marketplace, or membership platform.

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Creating Your First NFT with Move

To mint an NFT on Sui, you write a Move module that defines the structure and behavior of your token. Below is a simplified version of a basic NFT contract:

module examples::testnet_nft;
use std::string;
use sui::{event, url::{Self, Url}};

public struct TestnetNFT has key, store {
    id: UID,
    name: string::String,
    description: string::String,
    image_url: Url,
}

public fun mint_to_sender(
    name: vector<u8>,
    description: vector<u8>,
    url: vector<u8>,
    ctx: &mut TxContext,
) {
    let sender = ctx.sender();
    let nft = TestnetNFT {
        id: object::new(ctx),
        name: string::utf8(name),
        description: string::utf8(description),
        url: url::new_unsafe_from_bytes(url),
    };
    transfer::public_transfer(nft, sender);
}

This function allows any user to mint an NFT by providing a name, description, and image URL. While this model works for open mints, production applications often include restrictions—such as admin-controlled minting, limited supply caps, or permissioned access via mint tickets.

Controlling Who Can Mint

You can customize minting logic in several ways:

For rare or premium items, setting supply limits (e.g., only 2,000 available) preserves scarcity and value. In contrast, common in-game assets like starter characters or tools may have no cap to ensure accessibility.

Dynamic and Upgradable NFTs

Static profile picture (PFP) NFTs are popular, but Sui enables far more engaging experiences through upgradable and mutable NFTs.

Example: Leveling Up a Hero NFT

In gaming contexts, NFTs can evolve based on user actions. Consider a hero character that gains experience points and levels up:

public fun level_up_hero(
    hero: &mut Hero,
    ticket: LevelUpTicket,
    damage: u8,
    speed: u8,
    defense: u8,
) {
    let LevelUpTicket { id, hero_id, attribute_points } = ticket;
    assert!(object::borrow_id(hero) == &hero_id, EHeroIdMismatch);
    assert!(damage + speed + defense == attribute_points, EAttributePointsMismatch);
    object::delete(id);
    hero.level = hero.level + 1;
    hero.damage += damage;
    hero.speed += speed;
    hero.defense += defense;
}

Here, the player uses a LevelUpTicket (an owned object) to boost their hero's stats. Once used, the ticket is deleted—ensuring one-time use. This pattern enables verifiable scarcity and true digital ownership.

Redeemable NFTs

NFTs can also act as real-world redemption tokens. For instance, holders might exchange their NFT for physical goods—like a coffee or concert ticket. After redemption, the NFT’s status or image URL can be updated to reflect its used state.

Managing Off-Chain Data

While NFT ownership and core attributes live on-chain, associated media (images, videos) are typically stored off-chain due to size constraints. To ensure consistent display across apps like wallets and marketplaces, Sui supports the Object Display standard, which includes fields like image_url, name, and description.

Off-Chain Storage Options

Developers can choose between decentralized and centralized solutions:

The choice impacts durability and decentralization. For long-term projects, decentralized options offer greater resilience against data loss.

Even when data is off-chain, the source of truth remains the Sui blockchain. Apps can cache frequently accessed data for performance but should validate against on-chain state when necessary.

Wallet Integration: Enhancing User Experience

Managing private keys can be daunting for new users. Sui offers two key solutions to simplify access:

Invisible Wallets & zkLogin

With Invisible Wallets or zkLogin, users log in via familiar platforms (Google, Facebook, Twitch) without handling seed phrases. Your app manages the wallet behind the scenes while maintaining full blockchain compatibility.

These wallets allow seamless onboarding—ideal for games or consumer apps where UX is critical. Later, users can transfer their NFTs to self-custodial wallets like Sui Wallet for full control.

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Enabling Trading with Kiosks

When users take control of their wallets, you can use Sui Kiosks to enforce business rules—such as collecting royalties on secondary sales or restricting transfers unless conditions are met. This protects creators while enabling open marketplaces.

Tools and Standards You Should Know

Sui provides robust standards and developer tools:

Handling Broken Image URLs and Scams

When querying NFT data using suix_getOwnedObjects with showDisplay: true, you may encounter broken image URLs (404 errors). This is common due to abandoned projects or scam airdrops.

Always:

For example, an NFT claiming to represent token claims might link to a dead URL—indicating poor maintenance or malicious intent.

Frequently Asked Questions (FAQ)

Q: Can an NFT own another NFT on Sui?
A: Yes. Sui supports nested object ownership. For example, a game character NFT can own a weapon NFT.

Q: How do I prevent my NFT images from breaking over time?
A: Use decentralized storage like Walrus or IPFS with reliable pinning services to ensure long-term availability.

Q: What is zkLogin and how does it help with NFTs?
A: zkLogin lets users authenticate via social logins without managing private keys. It simplifies onboarding while preserving blockchain security.

Q: Can I upgrade my NFT after minting?
A: Yes. You can design mutable fields in your Move struct (like level or stats) and update them via approved functions.

Q: How do I limit who can mint my NFTs?
A: Implement access control in your Move contract using admin capabilities, mint tickets, or whitelist checks.

Q: Are there royalties on secondary sales?
A: Yes. Using Kiosks, you can enforce royalty payments when users resell in-game items or collectibles.

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