ERC721 vs. ERC721A

Maciej Zieliński

29 Mar 2022
ERC721 vs. ERC721A

Technology can be a great solution for many businesses and companies. Unfortunately, one of the unfortunate side effects is the amount of various technical jargon, which may be unintelligible to the average person. For the end-user, NFT often means little more than a decentralized collectors' item or a work of digital art. You can enjoy this industry without understanding how it works. But the trends in blockchain technology can be fascinating even for those who are not involved with creating it. Why are ERC721 and ERC721A so important in NFT? What makes it special and why should we learn about this technology? We're writing about this below!

What is ERC721?

Although blockchain technology is decentralized, we need a common language which will allow us to understand the data contained within it. As such, token standards like ERC721 become essential. It is a standard which works in a similar way to how all ports or plugs on various devices work. It is worth noting, for example, that formats such as PNG i JPEG, which are commonly associated with NFT, are by themselves image standards.
ERC721 is an extremely popular token standard for creating non-fungible tokens – NFT – on blockchains, such as Ethereum and Polygon. The letter ‘E’ in ‘ERC721’ stands for ‘Ethereum’ and is not the NFT standard that runs on blockchains that are incompatible with Ethereum portfolios such as Solana and Tezos.

​What makes ERC721 compliant tokens useful?

Below we outline some of the advantages of this solution:

  • Each token is unique (previously mentioned non-fungibility)
  • Each token can be transferred or sold
  • Owners can authorize other smart contracts to manage tokens

In addition, each of them is crucial to ensuring that NFT markets, such as OpenSea and LooksRare, can operate as intended. It should be pointed out that smart contracts are simply applications that live within blockchain technology. Seems complicated? It can be described in an even simpler way: ERC721 is a standardized way of creating unique blockchain tokens, which can be traded at markets.

​What is ERC721A?

Software developers in crypto typically use existing code libraries to simplify the development process of a project. When you write a code that's in the blockchain, there's even more pressure to use a battle-proven, existing code wherever possible, because blockchain technology prevents any code editing! In the NFT sector, a single open source code was widely accepted in order to enable the use of ERC721. Then there was the “Azuki” project, which quickly gained recognition in the NFT sector. In addition to the NFT issue itself, the project has created a new implementation of ERC721A.
The implementation of ERC721A is not meant to change the token standard. Its main purpose is to fit the token perfectly, but this task requires a number of other standards to be met, as opposed to ERC721 which has been used to date.
This has led to the reduction of the amount of gas needed to mint new NFT (especially those that are minted in batches).
The gas costs incurred in transferring NFT based on ERC721A to other persons at the original owner's prices are slightly higher. Overall, the gas savings that ERC721A can provide compared to ERC721 are excellent, but this solution cannot be implemented everywhere. For example, entities that do not mint NFT in bulk will still spend a significant amount of gas if we consider the transfer costs.

Let us remember that NFT provides many limitless possibilities not only for art, music, or sports. It is important to know and understand ERC721 and ERC721A, as this allows us to understand what NFT really is from its very basics. This makes us more aware of the direction in which this sector is developing. It is worth noting that while both implementations are important, they are neither the first nor last elements of NFT. They are the benchmark to follow.

How does ERC721A work?

ERC721A adopts specific conditions which then affect the smart contract project. This impact makes the following things happen:

  • Token IDs should always grow steadily – starting from zero. Currently, many NFT projects fulfill this condition.
  • The reduction of the gas costs related to minting NFT is the most important part of NFT production.

With these assumptions, ERC721A makes the following optimization of contracts:

  • Reduces the unused space, which is used to store metadata from tokens.
  • Limits ownership to one coin from the entire NFT batch.

Why is ERC721A so important?

Because it allows us to understand how high the gas charges really are, and what they result from! Reducing your work to sending transactions saves energy. At this point, we should emphasize that blockchain generates 2 types of transactions – reads and writes.

  • Write – occurs when we are doing something in a blockchain and its condition changes (for example, we sell NFT).
  • Read – it can be said that this is a review of the transaction file.

Users who use blockchain technology incur higher write costs than read costs. Therefore, if we reduce the pool of write information or transaction transfer requirements, we will reduce the cost of minting NFT.

What risks are involved with using ERC721A contracts for generating multiple NFT transactions?

TransferFrom and safeTransferFrom transactions cost more gas, which means that NFT can cost more from the moment of its minting. We should emphasize that using ERC721A leads to an increase in performance without the need to set owners of particular token ID.

For example, in the picture below there are two calls to mint a batch, one by Marcus to mint chips #100, #101, and #102 in one call, and the other by Brutus to mint chips #103 and #104

The above diagram shows that ERC721A must set up the property metadata twice, instead of 5 times – once for the Marcus package and once for the Brutus package. This is not so easy because by transferring a tokenID that does not have an owner address, the contract must create actions that include all tokenID’s in order to verify the original NFT owner. This is because the original owner has the right to move the token and set it to a new entity. Below we present a graph associated with this:

ERC721

The method of reading this chart is as follows: first move to the x-axis and then to the y-axis, for example:

  • „Mint a batch of 1 NFT, and then transfer tokenID 0”,
  • „Mint a batch 3 of NFT, and then transfer tokenID 1”
  • „Mint a batch 5 of NFT, and then transfer tokenID 4”

The above results indicate that moving token IDs in the middle of a larger mint batch (i.e. t1, t2) costs more than moving token IDs at the end of the batch (i.e. t0, t4).

How to minimize the cost of transferring an entire batch of NFT?

You can minimize costs if you are always minting the maximum allowed number of NFT when releasing an entire batch. In addition – when moving a batch, it is important to start a cycle with tokens of an ODD number in an ascending manner.
Examples of NFT projects using the ERC721A contract
Here is a list of projects, which are currently using the ERC721A contract:

  • @AzukiZen
  • @cerealclubnft
  • @TheLostGlitches
  • @standardweb3
  • @KittyCryptoGang
  • @XRabbitsClub
  • @WhaleTogether
  • @pixelpiracynft
  • @dastardlyducks
  • @MissMetaNFT
  • @StarcatchersNFT
  • @LivesOfAsuna
  • @richsadcatnft
  • @themonkeypoly
  • @womenofcrypto_
  • @TravelToucans
  • @HuhuNFT

Are ERC721A contracts still considered to be NFT transactions?

Of course. ERC721A contracts are NFT. Any contract that implements the ERC721 token standard, or the ERC1155 interfaces is seen as non-fungible or semi-fungible tokens. To put it simply, ERC721A is an extension and optimization of the previous version, the ERC721. The ERC721A contract is a very good idea which allows for saving money on gas in a given community, while at the same time protecting the Ethereum network from unnecessary workload.

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AI in Real Estate: How Does It Support the Housing Market?

Miłosz Mach

18 Mar 2025
AI in Real Estate: How Does It Support the Housing Market?

The digital transformation is reshaping numerous sectors of the economy, and real estate is no exception. By 2025, AI will no longer be a mere gadget but a powerful tool that facilitates customer interactions, streamlines decision-making processes, and optimizes sales operations. Simultaneously, blockchain technology ensures security, transparency, and scalability in transactions. With this article, we launch a series of publications exploring AI in business, focusing today on the application of artificial intelligence within the real estate industry.

AI vs. Tradition: Key Implementations of AI in Real Estate

Designing, selling, and managing properties—traditional methods are increasingly giving way to data-driven decision-making.

Breakthroughs in Customer Service

AI-powered chatbots and virtual assistants are revolutionizing how companies interact with their customers. These tools handle hundreds of inquiries simultaneously, personalize offers, and guide clients through the purchasing process. Implementing AI agents can lead to higher-quality leads for developers and automate responses to most standard customer queries. However, technical challenges in deploying such systems include:

  • Integration with existing real estate databases: Chatbots must have access to up-to-date listings, prices, and availability.
  • Personalization of communication: Systems must adapt their interactions to individual customer needs.
  • Management of industry-specific knowledge: Chatbots require specialized expertise about local real estate markets.

Advanced Data Analysis

Cognitive AI systems utilize deep learning to analyze complex relationships within the real estate market, such as macroeconomic trends, local zoning plans, and user behavior on social media platforms. Deploying such solutions necessitates:

  • Collecting high-quality historical data.
  • Building infrastructure for real-time data processing.
  • Developing appropriate machine learning models.
  • Continuously monitoring and updating models based on new data.

Intelligent Design

Generative artificial intelligence is revolutionizing architectural design. These advanced algorithms can produce dozens of building design variants that account for site constraints, legal requirements, energy efficiency considerations, and aesthetic preferences.

Optimizing Building Energy Efficiency

Smart building management systems (BMS) leverage AI to optimize energy consumption while maintaining resident comfort. Reinforcement learning algorithms analyze data from temperature, humidity, and air quality sensors to adjust heating, cooling, and ventilation parameters effectively.

Integration of AI with Blockchain in Real Estate

The convergence of AI with blockchain technology opens up new possibilities for the real estate sector. Blockchain is a distributed database where information is stored in immutable "blocks." It ensures transaction security and data transparency while AI analyzes these data points to derive actionable insights. In practice, this means that ownership histories, all transactions, and property modifications are recorded in an unalterable format, with AI aiding in interpreting these records and informing decision-making processes.

AI has the potential to bring significant value to the real estate sector—estimated between $110 billion and $180 billion by experts at McKinsey & Company.

Key development directions over the coming years include:

  • Autonomous negotiation systems: AI agents equipped with game theory strategies capable of conducting complex negotiations.
  • AI in urban planning: Algorithms designed to plan city development and optimize spatial allocation.
  • Property tokenization: Leveraging blockchain technology to divide properties into digital tokens that enable fractional investment opportunities.

Conclusion

For companies today, the question is no longer "if" but "how" to implement AI to maximize benefits and enhance competitiveness. A strategic approach begins with identifying specific business challenges followed by selecting appropriate technologies.

What values could AI potentially bring to your organization?
  • Reduction of operational costs through automation
  • Enhanced customer experience and shorter transaction times
  • Increased accuracy in forecasts and valuations, minimizing business risks
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Want to implement AI in your real estate business?

Nextrope specializes in implementing AI and blockchain solutions tailored to specific business needs. Our expertise allows us to:

  • Create intelligent chatbots that serve customers 24/7
  • Implement analytical systems for property valuation
  • Build secure blockchain solutions for real estate transactions
Schedule a free consultation

Or check out other articles from the "AI in Business" series

AI-Driven Frontend Automation: Elevating Developer Productivity to New Heights

Gracjan Prusik

11 Mar 2025
AI-Driven Frontend Automation: Elevating Developer Productivity to New Heights

AI Revolution in the Frontend Developer's Workshop

In today's world, programming without AI support means giving up a powerful tool that radically increases a developer's productivity and efficiency. For the modern developer, AI in frontend automation is not just a curiosity, but a key tool that enhances productivity. From automatically generating components, to refactoring, and testing – AI tools are fundamentally changing our daily work, allowing us to focus on the creative aspects of programming instead of the tedious task of writing repetitive code. In this article, I will show how these tools are most commonly used to work faster, smarter, and with greater satisfaction.

This post kicks off a series dedicated to the use of AI in frontend automation, where we will analyze and discuss specific tools, techniques, and practical use cases of AI that help developers in their everyday tasks.

AI in Frontend Automation – How It Helps with Code Refactoring

One of the most common uses of AI is improving code quality and finding errors. These tools can analyze code and suggest optimizations. As a result, we will be able to write code much faster and significantly reduce the risk of human error.

How AI Saves Us from Frustrating Bugs

Imagine this situation: you spend hours debugging an application, not understanding why data isn't being fetched. Everything seems correct, the syntax is fine, yet something isn't working. Often, the problem lies in small details that are hard to catch when reviewing the code.

Let’s take a look at an example:

function fetchData() {
    fetch("htts://jsonplaceholder.typicode.com/posts")
      .then((response) => response.json())
      .then((data) => console.log(data))
      .catch((error) => console.error(error));
}

At first glance, the code looks correct. However, upon running it, no data is retrieved. Why? There’s a typo in the URL – "htts" instead of "https." This is a classic example of an error that could cost a developer hours of frustrating debugging.

When we ask AI to refactor this code, not only will we receive a more readable version using newer patterns (async/await), but also – and most importantly – AI will automatically detect and fix the typo in the URL:

async function fetchPosts() {
    try {
      const response = await fetch(
        "https://jsonplaceholder.typicode.com/posts"
      );
      const data = await response.json();
      console.log(data);
    } catch (error) {
      console.error(error);
    }
}

How AI in Frontend Automation Speeds Up UI Creation

One of the most obvious applications of AI in frontend development is generating UI components. Tools like GitHub Copilot, ChatGPT, or Claude can generate component code based on a short description or an image provided to them.

With these tools, we can create complex user interfaces in just a few seconds. Generating a complete, functional UI component often takes less than a minute. Furthermore, the generated code is typically error-free, includes appropriate animations, and is fully responsive, adapting to different screen sizes. It is important to describe exactly what we expect.

Here’s a view generated by Claude after entering the request: “Based on the loaded data, display posts. The page should be responsive. The main colors are: #CCFF89, #151515, and #E4E4E4.”

Generated posts view

AI in Code Analysis and Understanding

AI can analyze existing code and help understand it, which is particularly useful in large, complex projects or code written by someone else.

Example: Generating a summary of a function's behavior

Let’s assume we have a function for processing user data, the workings of which we don’t understand at first glance. AI can analyze the code and generate a readable explanation:

function processUserData(users) {
  return users
    .filter(user => user.isActive) // Checks the `isActive` value for each user and keeps only the objects where `isActive` is true
    .map(user => ({ 
      id: user.id, // Retrieves the `id` value from each user object
      name: `${user.firstName} ${user.lastName}`, // Creates a new string by combining `firstName` and `lastName`
      email: user.email.toLowerCase(), // Converts the email address to lowercase
    }));
}

In this case, AI not only summarizes the code's functionality but also breaks down individual operations into easier-to-understand segments.

AI in Frontend Automation – Translations and Error Detection

Every frontend developer knows that programming isn’t just about creatively building interfaces—it also involves many repetitive, tedious tasks. One of these is implementing translations for multilingual applications (i18n). Adding translations for each key in JSON files and then verifying them can be time-consuming and error-prone.

However, AI can significantly speed up this process. Using ChatGPT, DeepSeek, or Claude allows for automatic generation of translations for the user interface, as well as detecting linguistic and stylistic errors.

Example:

We have a translation file in JSON format:

{
  "welcome_message": "Welcome to our application!",
  "logout_button": "Log out",
  "error_message": "Something went wrong. Please try again later."
}

AI can automatically generate its Polish version:

{
  "welcome_message": "Witaj w naszej aplikacji!",
  "logout_button": "Wyloguj się",
  "error_message": "Coś poszło nie tak. Spróbuj ponownie później."
}

Moreover, AI can detect spelling errors or inconsistencies in translations. For example, if one part of the application uses "Log out" and another says "Exit," AI can suggest unifying the terminology.

This type of automation not only saves time but also minimizes the risk of human errors. And this is just one example – AI also assists in generating documentation, writing tests, and optimizing performance, which we will discuss in upcoming articles.

Summary

Artificial intelligence is transforming the way frontend developers work daily. From generating components and refactoring code to detecting errors, automating testing, and documentation—AI significantly accelerates and streamlines the development process. Without these tools, we would lose a lot of valuable time, which we certainly want to avoid.

In the next parts of this series, we will cover topics such as:

Stay tuned to keep up with the latest insights!