Choosing a smart contract: ERC-721 vs ERC-721a

Smart contracts are the powerhouses behind non-fungible tokens (NFTs): they are essentially the “blueprint” establishing the properties of the tokens, and the “factory” used to create them. If you’re launching your own NFT project, you’ll want to deploy your own smart contract. Doing so enables you to fully leverage the power of NFTs and create advanced utility features to engage and incentivize your users.

ERC-721: the tried and true standard

Until recently, the standard OpenZeppelin implementation of the ERC-721 smart contract was the clear choice for NFT creators. It is the original smart contract for creating non-fungible digital assets, where each NFT has its own token ID. It’s the most widely used, well-known contract available, and has been trusted by countless NFT projects since the inception of the technology.

There’s just one (fairly significant) catch. It’s not cheap. The way this particular smart contract deals with minting (creating) new NFTs happens to use a lot of computing power, which has to be paid for in blockchain transaction (gas) fees.

These exorbitant gas fees have been simply accepted as the price to be paid for minting NFTs on Ethereum. Of course, you can use a less popular blockchain with lower gas fees, but if you want to launch your collection on the most popular and trusted blockchain with the most trusted smart contract standard, ERC-721 has really been the only choice for a while now.

Enter ERC-721a

The NFT studio Chiru Labs, creators of the iconic Azuki NFT collection, however, decided to do something about it. After launching numerous collections and observing user behavior, they realized certain parameters within the smart contract that used huge amounts of computing power (thus resulting in higher gas fees) were not necessary for the vast majority of projects. By optimizing the mapping of these parameters, they could help both NFT creators and buyers save big on gas fees when minting multiple NFTs, while still using Ethereum and almost all of the features that make the original ERC-721 standard great.

So how much can ERC-721a save you on minting? A LOT. According to Azuki’s calculations (assuming a price of 300 gwei), after batch minting just 5 NFTs in one transaction, the ERC-721a smart contract can save over $500 in gas fees. This is no pocket change to scoff at: for projects minting all their NFTs themselves in advance, it’s the difference between having crippling overheads and almost insignificant costs.

We've run our own tests at Artiffine as well, and the difference between the two contracts as you batch mint more and more tokens is astonishing:

But, is there a catch?

Well, yes and no. As pointed out by Alchemy in their article on the new standard, the same optimizations that reduce minting costs can make transfers of the NFT after minting more expensive for NFT holders. However, there are workarounds for these more expensive transfer costs, so it’s not necessarily a huge tradeoff.

So which smart contract should I choose?

If your users won't be minting multiple tokens, then the original ERC-721 contract remains a popular choice for many projects. The ERC-721a standard is only more gas efficient in batch minting scenarios.

If your users are batch minting NFTs, then the gas savings offered ERC-721a contract is the clear winner. It will save your community massively on gas costs and make your collection more appealing at the primary sale. Think of it this way: if each user minted 2 NFTs, saving $26 on gas, and sold out your 10,000 NFT collection, your community would save a total of $130,000!

How do I make a smart contract?

Now, this is the part that is easier said than done, as coding and deploying smart contracts is work for experienced developers. If you’re not one, you might find it prohibitively difficult. 

Not to worry, though, this is where Artiffine can help. Our experienced web3 developers can implement custom smart contracts with either standard into your NFT project, depending on your requirements. We can also help advise you on which contract, pricing structure, or go-to-market strategy would be best for your particular use case, and our UI/UX and design teams can build flawless user experiences to make your launch go off with a bang. To provide a solid legal foundation for your launch, our legal team can take care of NFT licensing and any compliance issues you might have.

If you need a trusted partner to launch your collection, or if you just need some help at any stage in the process get in touch. Our Solution Architects will be more than happy to discuss the options available and always love to hear about new and interesting NFT projects!

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