ERC-721A

ERC-721A is an implementation of the ERC-721 NFT standard (the IERC721 interface) optimized to drastically lower the cost of batch minting several tokens in a single transaction, while keeping full ERC-721 compatibility. The distinction is worth making: it is not an EIP with a number assigned by the official repository, nor does it change the IERC721 interface. It is a reference library published by Chiru Labs, the team behind Azuki, and the name "ERC-721A" works as the brand of that implementation, not as a new interface standard.

The mechanism removes the redundant cost of updating ownership storage for every token. Instead of writing the owner for each tokenId, it writes ownership once per batch and derives the intermediate owners at read time, and it avoids costly structures such as the ERC721Enumerable overhead. According to the project itself, a user can mint several tokens for a gas cost close to minting a single one with standard ERC721Enumerable. The known trade-off is that later transfers of tokens from a batch can cost slightly more gas, a deferred cost of reading and writing ownership.

The Azuki team publicly announced ERC-721A around 6 January 2022 and used it in their 12 January 2022 sale, where 8,700 tokens were offered to the public and minted within minutes. It has since been widely adopted as a library, becoming the de facto standard for batch minting collections. Where tokenization uses NFTs to represent unique assets, ERC-721A optimizes issuance cost, not compliance. For a regulated RWA the relevant standard is ERC-3643 (T-REX), which provides permissioning and identity; ERC-721A and ERC-3643 solve different problems.