Semi-fungible token (SFT)

The term covers two distinct approaches that should not be confused. ERC-1155, the Multi Token Standard by Witek Radomski, Andrew Cooke and the Enjin team, reached final status in June 2019. A single contract manages multiple token ids, each with its own supply, and allows fungible and non-fungible tokens together, with batch transfers that cut gas compared to deploying one ERC-721 per item. Here semi-fungibility means an id can be treated as fungible until used and then as unique. ERC-3525, proposed in 2020 and final in September 2022, uses a triple-scalar model of ID, SLOT and VALUE: each token has a unique id, belongs to a slot and carries a divisible, partially transferable numeric value.

Each approach solves different cases. ERC-1155 fits gaming, where a single contract manages coins, consumables and unique items, as well as ticketing and batch collections. ERC-3525 is designed for fractionalizable financial instruments such as bonds, token vesting and RWA where both a unique identity and a divisible quantity are needed, for example a bond with a fractionalizable principal.

Enjin drove the ERC-1155 standard for video-game assets, and The Sandbox builds its game assets on that same standard. Solv Protocol uses ERC-3525 to represent tokenized bonds and financial vouchers, leveraging the divisible numeric value to fractionalize the instrument while keeping its unique identity, which illustrates the standard's fit in finance.