ERC-998: Composable NFTs on the Ethereum Blockchain


The Ethereum blockchain has revolutionized the concept of digital ownership with its implementation of Non-Fungible Tokens (NFTs). While the ERC-721 standard laid the foundation for NFTs, it posed limitations in representing complex ownership structures. Enter ERC-998, an extension of ERC-721, designed to address these limitations and introduce a new era of composable NFTs.

What is ERC-998?

ERC-998 stands as a standardized contract interface that extends the functionalities of ERC-721 tokens. It introduces the concept of composability, allowing an NFT to own other NFTs (ERC-721) or fungible tokens (ERC-20). This enhancement enables the creation of hierarchical relationships between digital assets, transforming how we perceive and interact with them on the blockchain.

Types of ERC-998 Tokens

Top-Down Composability

Top-down composable tokens manage collections of child tokens, which can be NFTs or fungible tokens. This model is exemplified in gaming, where in-game characters possess individual items like weapons and armor.


Bottom-up composable tokens are attached or linked to parent NFTs, often serving as non-transferable badges of achievement or certifications. These tokens enhance the profile of the parent NFT, adding layers of value and authenticity.

ERC-998 Bottom-up Composable

Key Features and Capabilities

ERC-998 introduces hierarchical ownership, enabling the creation of complex ownership structures and nested token relationships. Transferability is simplified, as entire asset compositions can be transferred in a single transaction. Additionally, atomic transactions ensure the integrity of composite token transfers by transferring all child tokens together with the parent token or none at all.

Use Cases of ERC-998


In gaming, ERC-998 facilitates the representation of complex in-game assets, simplifying ownership, management, and trading.

Digital Collectibles

Collections of NFTs can be bundled as single ERC-998 tokens, streamlining ownership and enhancing market accessibility.

Real-World Asset Representation

ERC-998 tokens can revolutionize the representation of real-world assets on the blockchain, enabling fractional ownership and easier transfers.

Identity and Credentials

Non-transferable achievements and certifications can be securely linked to identity NFTs, providing a verifiable showcase of one’s accomplishments.

Advantages and Limitations

ERC-998 offers increased versatility and novel use cases across various industries. However, limitations such as gas costs and lack of support from certain NFT marketplaces and wallets need to be considered.


ERC-998 represents a significant advancement in NFT technology, unlocking new possibilities for digital asset management and transferability. Its hierarchical ownership and composability features pave the way for innovation in gaming, digital collectibles, real-world asset representation, and identity verification. While challenges persist, ERC-998 stands as a beacon of opportunity, encouraging experimentation and growth in the NFT ecosystem.

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