What the Heck is ERC721? ERC721A?
There's a lot of technical jargon in the NFT world. ERC721A gains increasing attention, but what even is it?
Technology can be downright magical, but one of the unfortunate side effects is all sorts of technical jargon that can be indecipherable to the average person. Even those experienced with minting Ethereum NFTs might be able to appreciate that the cost to mint Dastardly Ducks was low or that it utilized something created by a big project, Azuki, but the term “ERC721A” means little.
To the end user, an NFT often functions as little more than a decentralized collectible or piece of digital art. One can easily enjoy this industry without understanding how things function. But the trends in technology can be fascinating even for those not actively building with them.
ERC721 (no A)
First let us talk about ERC721 — with no “A” on the end. Though blockchains are decentralized, we need a shared language with which to understand the data on there. This is where token standards like ERC721 come in handy. This is a standard much in the same way any ports or plugs on your device follow a standard. Even formats like PNG and JPEG linked to frequently by NFTs are, themselves, image standards.
ERC721 is an extremely popular token standard for making non-fungible tokens — NFTs — on blockchains like Ethereum and Polygon. The “E” in “ERC721” stands for “Ethereum,” and it is not an NFT standard that works on blockchains incompatible with Ethereum wallets like Solana and Tezos.
What things make a token that follows the ERC721 spec useful?
Each token is unique (the aforementioned non-fungibility)
Each token can be transferred or sold
Owners can authorize other smart contracts to manage tokens
Each of these is a critical part of ensuring that NFT marketplaces like OpenSea and LooksRare can function as intended. The “smart contracts” are just applications that live on the blockchain — when one makes a transaction on these sites, their own smart contracts are used.
All of this might be a lot to non-technical users, but, simply put: ERC721 is a standardized way of making unique blockchain tokens that can be easily traded in marketplaces.
ERC721A (with an A)
Software developers routinely reuse existing libraries of code to simplify the development process. When writing code that lives on the blockchain — which can never be modified after release! — there is even more of a pressure to use battle-tested, pre-existing code wherever possible. For NFTs, this led to widespread adoption of the same open source code to make ERC721 work.
Then came a project known as Azuki. With an anime style almost reminiscent of Cowboy Bebop, it quickly made a name for itself in the NFT space upon release in January 2022. However, they released more than the NFTs. They released a new implementation of ERC721 called ERC721A.
ERC721A does not seek to change the token standard. Rather, it is designed to perfectly fit within it. However, it takes a radically different approach to fulfilling what the standard demands compared to the code previously in widespread use for ERC721.
This greatly reduces the amount of gas needed to mint new NFTs, especially for NFTs minted together in batches — a basically arbitrary amount can be minted with very little extra gas spent. In the case of Dastardly Ducks, by offering 12-packs at an affordable price, we managed to use an absurdly low amount of gas on minting.
The gas costs when transferring ERC721A-based NFTs to others after the original owner mints it are slightly higher. The overall gas savings it can provide are impressive, but it is not a one-size-fits-all approach. Projects where people do not mint in bulk will undoubtedly wind up spending more gas in the end, when transfer costs are included.
NFTs provide a lot of interesting opportunities for more than just art. While those of us who are tech-savvy should strive to make these technologies available through an experience your grandmother could navigate, understanding what NFTs truly are on an engineering level can help you fully understand this emerging industry and its potential applications.
Just keep in mind that ERC721 — and the specific method of implementing it in ERC721A — are not the be-all and end-all of NFT technology. This is merely a well-trodden path with an interesting new shortcut. We can give you a map, but not the right path for you to take.
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