ERC404 tokens are hybrid, semi-fungible tokens that enable native liquidity and fractionalization for NFTs via mixed use of ERC20 and ERC721 functions. Tentative to it's eventual EIP, it is an experimental and open-sourced token standard that has not yet been recognized by the Ethereum Foundation as an official token standard.

The two core innovations enabled by ERC404 are native liquidity for non-fungible tokens and fractionalization without the use of external protocols or "wrappers" that abstract non-fungible tokens from their collection of origin. This vastly improves upon the user experience for NFT collectors and market participants alike, and unlocks a new asset category that is best described as semi-fungible tokens or "SFTs".

We believe that ERC404 is a major innovation that enables various interactive mechanics and new on-chain protocols for both fungible and non-fungible tokens. It's hybrid nature allows for various applications that combine the affordances of ERC20 and ERC721 tokens, giving way to a plethora of new use cases across gaming, generative art, real world assets or "RWAs", and more.

ERC404 is entirely open-source and freely accessible for both developers and creators alike. We highly encourage the exploration of ERC404s various applications as a nascent token standard, and actively maintain the public repo as well as thorough documentation on the design, development, and implementation of the token standard. Developer incentives and grants for ecosystem partners are also in the works and will be announced via the official Pandora Twitter account.

Not quite yet. 404 is a common error message meaning "not found" in various applications and websites. It's a naming convention that was designed to make ERC404 easier to intuit as a new kind of token, with an experimental design that we knew would confuse many protocols and dApps on launch as a result of it's experimental nature and the introduction of mixed ERC721 and ERC20 functions.