ERC-1155 vs ERC-3525: Semi-Fungible Token (SFT) Implementation

Single-contract multi-asset management: Transfer multiple token types (fungible, non-fungible, semi-fungible) in one transaction. This reduces gas costs by up to 90% for minting and trading game items (e.g., OpenSea bundles) or NFT collections.

Widespread adoption and tooling: Supported by all major marketplaces (OpenSea, Rarible), wallets (MetaMask), and gaming engines (Unity, Unreal via SDKs). Over 4M+ contracts deployed, making it the de facto standard for gaming and digital collectibles.

Slot/ID structure for complex assets: Each token has a slot (fungible class) and an ID (unique instance), enabling native representation of financial instruments like bonds, insurance policies, or loyalty points with built-in transfer logic.

Programmable value storage: Tokens can hold and transfer internal values (e.g., a bond's coupon amount) and execute logic via approved operators. This is critical for DeFi protocols like Solv Protocol creating convertible vouchers or vesting schedules.

Flat metadata structure: While efficient for bundles, it lacks native mechanisms for representing hierarchical or stateful relationships between tokens, making complex financial logic cumbersome to implement on-chain.

Early-stage ecosystem: Limited direct support from mainstream wallets and marketplaces. Requires custom front-ends and deeper integration work, increasing development overhead compared to plug-and-play ERC-1155 solutions.

Single-contract, multi-token standard: Enables minting, transferring, and balancing thousands of token types (fungible, non-fungible, semi-fungible) in a single transaction. This reduces gas costs by up to 90% for operations like initial game item distribution or marketplace listings. Critical for gaming (The Sandbox) and NFT collections with multiple traits.

Wide tooling and marketplace support: Integrated by default in OpenSea, Rarible, and major game engines. Over 4,000+ contracts deployed on Ethereum mainnet, with libraries like OpenZeppelin providing battle-tested implementations. The de facto standard for metaverse assets and digital collectibles, minimizing integration risk.

Simple id-based mapping: Tokens are defined by an ID and a supply, with metadata stored off-chain (URI). Lacks native, on-chain structure for complex state or relationships. This makes it poorly suited for financial instruments like bonds or insurance policies that require internal, programmable value slots.

No intrinsic value subdivision: While you can have multiple copies of a token ID (semi-fungibility), you cannot programmatically split, merge, or recombine value within a single token ID. This limits its use for DeFi positions or loyalty points that need dynamic internal accounting.

Slot-and-Value architecture: Each token has a unique ID (like NFT) and a slot that defines its type. The value within a slot is fungible and can be transferred, split, and merged without changing the token ID. Ideal for Real-World Asset (RWA) tokens, bonds, and insurance policies where the underlying value changes.

Native support for complex logic: Tokens can hold and transfer other tokens (ERC-20, ERC-721) via the IERC3525Receiver interface, enabling self-contained financial products. This allows for the creation of on-chain vesting schedules, option contracts, and multi-asset baskets within a single token standard.

Emerging, specialized standard: Limited deployment compared to ERC-1155, with fewer than 100 mainnet contracts. Tooling (wallets, explorers, marketplaces) requires custom integration. Higher implementation risk for projects targeting mass consumer applications versus specialized DeFi or institutional finance.

Steeper development overhead: The slot/value model and receiver interface introduce conceptual and implementation complexity beyond simple asset representation. Auditing and security review is more critical. Best suited for teams with deep smart contract expertise building structured financial products, not simple digital items.