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Exploring ERC404: A Hybrid Token Standard Built On Ethereum

Published on: Feb 8, 2024
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In Brief

Dive into the innovative world of ERC404, a hybrid token standard merging ERC20 and ERC721 tokens on Ethereum. Learn how it works, including the risks for users and opportunities for Ethereum.

Exploring ERC404: A Hybrid Token Standard Built On Ethereum


The Ethereum blockchain is renowned for its adaptability and the continuous evolution of token standards, which enhance the protocol’s functionality and utility. Among these innovations is the ERC404 standard, an unofficial hybrid token model that aims to bridge the gap between fungible tokens (like ERC20) and non-fungible tokens (NFTs, such as ERC721). This blog post delves into the essence of ERC404, its first application through the Pandora project, and why its emergence could be a pivotal development for Ethereum.

Note: Please note that although ERC404 has been independently audited, it currently has not been officially recognized as a token standard within the Ethereum ecosystem. This fact can potentially put your assets at risk, should you decide to interact with any ERC404 project. This article aims to inform and should not be seen as an endorsement of ERC404 projects, nor is it intended as financial advice. We encourage you to proceed with caution and do your own research before interacting with any ERC404 project.

What is ERC404?

At its core, ERC404 represents an experimental token standard developed by the Pandora team. It uniquely combines the fungibility of ERC20 tokens with the uniqueness and collectibility of ERC721 NFTs. This hybrid approach allows for the creation of tokens that possess both qualities, offering new possibilities for digital asset ownership and trading.

It's crucial to note that at the time of this article’s writing, ERC404 has not undergone the official Ethereum Improvement Proposal (EIP) process, which is the standard procedure for vetting and adopting new features or changes within the Ethereum ecosystem. This process ensures that proposals are thoroughly discussed and scrutinized by the community, assessing their security, utility, and compatibility.

The official EIP process typically goes through stages as follows:

It’s important to note that the Ethereum Improvement Proposal (EIP) process plays a crucial role in the development and evolution of the Ethereum blockchain. This formal process is vital for maintaining the blockchain's integrity, security, and forward momentum.

With this in mind, ERC404's status remains unofficial, which means it’s yet to be formally recognized or endorsed by the Ethereum Foundation. Although we cannot say if this will change or not, you can stay updated by periodically checking the official Ethereum Improvement Proposal page.

There are a number of ERC404 tokens gaining popularity, including Pandora, DeFrogs, and more. Here’s a list of tokens that are trending at the time of writing.


The Birth of Pandora: ERC404 in Action

Pandora, the inaugural project to utilize the ERC404 standard, has introduced a compelling use case with its offering of 10,000 ERC20 tokens and an equivalent number of "Replicant" NFTs. When a user purchases a full Pandora token, a corresponding Replicant NFT is minted to their wallet.

Conversely, selling a Pandora token results in the burning of the linked NFT, showcasing a dynamic interaction between the two asset types​​.This process is not only innovative but also introduces a layer of engagement and strategy for token holders, as the rarity of the NFTs becomes a pivotal factor in the ecosystem's dynamics.

The Concept of Rarity

The concept of rarity plays a significant role in the Pandora project. Each Replicant NFT minted possesses a unique rarity, influencing its value and desirability within the community. This system encourages users to engage in trading activities, not just for the sake of liquidity but also to "reroll" the rarities of the NFTs they receive. It's a gamified approach that adds depth to the project, encouraging active participation and investment in the ecosystem.

The rarity system within Pandora significantly amplifies the project's allure, making each NFT not just a token but a treasure, potentially ripe for discovery. As participants dive into the ecosystem, the thrill of uncovering or trading for a highly rare NFT adds an extra layer of excitement and competition. This aspect of Pandora cleverly taps into the human penchant for collecting and the joy of the hunt, making each interaction within the marketplace an adventure in itself.

Moreover, this emphasis on rarity has broader implications for the NFT market as a whole. By integrating such a system, Pandora not only enhances user engagement within its own ecosystem but also sets a precedent for how value and desirability can be constructed in digital spaces. This approach could inspire other projects to adopt similar mechanisms, potentially leading to more vibrant and active NFT communities. As users become more invested in the outcomes of their trades, we might see a deeper, more nuanced understanding of value emerge in the world of digital collectibles.

The Potential and Risks of ERC404

Despite its experimental and unofficial status, ERC404 has captured the attention of the crypto community, as evidenced by the significant trading activity surrounding Pandora and other ERC404 projects. This interest underlines the potential of ERC404 to innovate how digital assets are created, traded, and valued. However, the ERC404 standard also carries risks associated with its the lack of formal recognition, which could expose users to unforeseen vulnerabilities.

ERC404 Safety Tips

If you decide to explore ERC404 projects, we encourage you to use a secure crypto wallet and proceed with caution. Here are a few tips to help you explore more safely.

ERC404 Safety Tip #1: Remember, It’s an Unofficial Standard (Security Risk)

ERC404 has not undergone the official Ethereum Improvement Proposal (EIP) process. Also, because ERC404 is not an official Ethereum standard, interacting with projects built on the standard poses security risks, including the risk of losing funds. We encourage you to do your own research and understand the risks before interacting with any ERC404 project.

ERC404 Safety Tips #2: Check Token Contracts Before Swapping

It’s always a good idea to check the token contract before swapping your existing crypto for ERC404 tokens on decentralized exchanges (DEXs). Checking proactively helps you avoid interacting with fake tokens and projects. For instance, you can check the token contract for Pandora on CoinMarketCap, then ensure the token you’re interacting with on DEXs matches.


ERC404 Safety Tips #3: Beware of Fake Projects and Scams

New trends often attract bad actors and scammers, who create fake tokens and websites. Be sure to get your information about ERC404 projects from the official websites and social accounts. Ensuring you have the correct link means you can locate the correct projects on DEXs, as well as, NFT platforms such as OpenSea.

You can also use CoinMarketCap to access the official links for projects. Learn more about how to avoid crypto scams.



ERC404 stands as a testament to the openness and innovation within the Ethereum ecosystem. While the Pandora project has demonstrated the practical application and interest in such a hybrid model, the broader adoption and impact of ERC404 remain to be seen. Whether ERC404 becomes a footnote or a foundational element in the history of Ethereum, its development and reception underscore the vibrant and dynamic nature of Web3.


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Note: Any cited numbers, figures, or illustrations are reported at the time of writing, and are subject to change.

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