The Fungibility of Non-Fungible Tokens: A Quantitative Analysis of ERC-721 Metadata

Abstract: Non-Fungible Tokens (NFTs), digital certificates of ownership for virtual art, have until recently been traded on a highly lucrative and speculative market. Yet, an emergence of misconceptions, along with a sustained market downtime, are calling the value of NFTs into question. This project (1) describes three properties that any valuable NFT should possess (permanence, immutability and uniqueness), (2) creates a quantitative summary of permanence as an initial criteria, and (3) tests our measures on 6 months of NFTs on the Ethereum blockchain, finding 45% of ERC721 tokens in our corpus do not satisfy this initial criteria. Our work could help buyers and marketplaces identify and warn users against purchasing NFTs that may be overvalued.