ERC-6909

ERC-6909 keeps balances per owner and token id pair in a single contract, just like ERC-1155, but trims the extras. It includes no receive callbacks, so it does not force the recipient to implement hooks, which saves gas and complexity. It also has no native batching in its minimal interface. Its permission system is hybrid: it combines granular approvals per id and amount, infinite approval per id, and operators with full permission over all ids, which is finer than ERC-1155's all-or-nothing operator scheme. The result is lower gas on deployment, transfers and burns, with smaller contracts.

It fits singleton architectures, where one contract represents many assets or positions without deploying a contract per asset, for example internal claims of an AMM. It is useful precisely in cases where ERC-1155 callbacks are unnecessary and only add gas. It shares its minimal philosophy with ERC-7579 and ERC-5192: standards that define the essentials and delegate the rest to the implementer.

The standard, titled Minimal Multi-Token Interface, was proposed in April 2023, authored by JT Riley, Dillon Kellar, Sara, Vectorized and Neodaoist, and is marked Final in the official specification. Its reference case is Uniswap v4, which adopts it as an internal settlement layer: the PoolManager, a singleton contract, holds ERC-6909 representations of users' tokens instead of moving ERC-20 in and out on every operation, which cuts gas on multi-hop swaps. Uniswap v4 launched in January 2025. Interface adoption does not guarantee each implementation’s security.