A censorship-resistant NFT auction marketplace that lets anyone upload digital art to IPFS, auction it, and tokenize it as an ERC-721 NFT ($ART) — all without centralized control.

Install all dependencies:

npm install

Required packages:

• ipfs-http-client@^49.0.2

Solidity compiler version:

• ^0.6.3

1. Connect your MetaMask wallet to Rinkeby Testnet

2. Start the development server:

   npm run start

This DApp allows users to:

• Upload digital artwork to IPFS
• Start an on-chain auction for the art
• Set custom auction rules (price, increment, duration)
• Once sold, mint the artwork as an ERC-721 NFT ($ART)

When starting an auction, the seller must specify:

• price: Minimum starting price
• _bidIncrement: Fixed minimum increment for new bids (prevents spam bidding and bots)
• tokenURI: IPFS CID hash for the artwork

There are two types of token IDs tracked:

• _tokenIds: Unique IDs for tokenized (minted) images
• _artItemIds: Unique IDs for artworks listed for auction (not yet tokenized)

Each artwork's bidding data is mapped as:

mapping(uint256 => mapping(address => uint256)) public fundsByBidder;

struct ArtItem {
    address payable seller;
    uint256 minbid;
    string tokenURI;
    bool exists;
    uint bidIncrement;
    uint time;
    uint timePeriod;
    bool cancelled;
    bool auctionstarted;
}

struct bidding {
    uint highestBindingBid;
    address payable highestBidder;
}

There are two types of bid amounts tracked:

• highestBid: The max bid submitted
• highestBindingBid: The max bid that counts (based on increment logic)

If Bidder B later bids 12 ETH, Bidder A’s new highestBindingBid becomes 13 ETH, maintaining a fair lead.

When the auction ends, the NFT is minted for the highestBindingBid, and any excess ETH is refunded to the highest bidder.

• Overbidding oneself is prevented
• Underbidding against the current highestBindingBid is disallowed
• Edge cases for tied bids or late entries are handled

This contract uses the withdrawal pattern to securely allow bidders to withdraw excess funds, reducing the risk of reentrancy attacks:

function withdraw() public {
    // safely withdraw user’s available balance
}

• The contract is fully decentralized, with no owner
• Anyone can list, bid, or mint artwork
• All art metadata is stored on IPFS
• Even if the frontend is shut down, the smart contract remains functional and accessible via direct interaction (e.g., Etherscan or scripts)

Run a local development environment (e.g., Ganache):

truffle migrate
truffle test

• Upload → Auction → Mint → Trade — fully decentralized.
• Auction is governed by transparent rules and protected from spam or manipulation.
• IPFS + Ethereum ensures that neither your art nor your marketplace can be taken down.