ERC-721 / Ordinals NFT Metadata Validator, IPFS CID Inspector & Dutch Auction Lab (2026)

CIDv0 is a legacy 46-character Base58btc-encoded string that always starts with `Qm` (implicitly specifying SHA-256 and dag-pb protobuf). Because Base58btc is case-sensitive, CIDv0 cannot be used safely inside case-insensitive DNS subdomain gateways (`https://<cid>.ipfs.dweb.link`). CIDv1 adds self-describing multiformats headers (version, multicodec like `dag-pb` or `raw`, and multihash) encoded in case-insensitive Base32 (`bafybeig...`).

IPFS (InterPlanetary File System) guarantees **content integrity** (a CID always hashes to the exact same bytes), not **automatic persistence**. If no IPFS node on the DHT network actively 'pins' (stores and serves) the blocks associated with that CID and garbage collection runs, the asset becomes unreachable unless backed by pinning services (Pinata, Filecoin) or Arweave.

Older rarity tools simply added `1 / (trait_count / total_supply)`, which artificially inflated items with more trait categories. OpenRarity applies Claude Shannon's Information Theory: the information content (surprisal) of a trait occurring with probability `P` is `-log2(P)` bits. Summing `-log2(P_i)` across all trait categories and normalizing by expected collection entropy produces a mathematically sound rarity score.

When demand exceeds supply in a fixed-price mint, buyers compete by bidding up blockchain priority gas fees, transferring millions of dollars in value to block validators rather than the artist and failing thousands of reverted transactions. A Dutch Auction starts above market clearing value and steps down at fixed intervals (e.g., every 10 minutes) until supply sells out at true market price discovery.

In a standard Dutch Auction, early bidders pay a higher price than later bidders, causing buyers to hesitate ('chicken game'). In a Clearing-Price Rebate Dutch Auction, everyone who bids early at 2.0 ETH or 1.5 ETH is automatically entitled to claim a smart-contract refund down to the final sell-out clearing price (e.g., 0.8 ETH), encouraging honest early bidding.