Glossary
ERC-6909
A gas-efficient multi-token standard — like ERC-1155 but with a simpler interface and no transfer hooks, designed for high-throughput accounting in protocols.
ERC-6909 is a minimal multi-token interface — one contract holds balances of many token IDs, similar to ERC-1155 — but stripped of the safe-transfer hooks and operator-approval surface that make ERC-1155 expensive and tricky for protocol internals.
The standard targets cases where a protocol wants its own internal multi-token accounting (Uniswap v4 uses it for pool tokens, lending markets for share tokens) without the gas and audit cost of ERC-1155. ERC-6909 is now the default choice for in-protocol multi-token state.