ERC1155

ERC-1155, or Ethereum Request for Comment 1155, is a token standard on the Ethereum blockchain designed to manage multiple token types within a single smart contract. It supports fungible tokens, non-fungible tokens (NFTs), and semi-fungible tokens, enabling a mixed asset portfolio under one contract rather than separate contracts for each token type. The standard is intended to improve efficiency for games and other platforms that handle many assets.

Token types are identified by unique IDs. Balances are tracked per account per ID. The protocol provides balanceOf, balanceOfBatch, setApprovalForAll, and isApprovedForAll, along with transfer functions safeTransferFrom and safeBatchTransferFrom. Transfers emit TransferSingle and TransferBatch events to enable client synchronization.

Metadata is exposed via a URI function. Each token ID maps to metadata, with a URI template allowing clients to substitute the ID for metadata location. The interface is ERC-165 compliant, and supportsInterface enables compatibility checking with other contracts. The interface identifier for ERC-1155 is 0xd9b67a26.

Gas efficiency is a core feature: batch transfers can move multiple token types in a single transaction, reducing gas compared with multiple distinct contracts. This design makes ERC-1155 popular for gaming assets, in-game currencies, and other digital collectibles where many token types may be created and traded.

Open-source implementations and adoption: OpenZeppelin provides audited ERC-1155 contracts, and many projects implement the standard directly. Developers should consider security implications of approvals and batch operations, and regularly audit smart contracts that manage valuable tokens.