What are the different NFT standards (e.g., ERC-721, ERC-1155)?

Understanding NFT Standards and Their Role in Blockchain Ecosystems

NFT standards define the rules and technical specifications for creating and managing non-fungible tokens on blockchain platforms. These standards ensure interoperability, security, and consistency across decentralized applications (dApps), wallets, and marketplaces. The most widely adopted NFT standards are built on the Ethereum blockchain, although similar standards exist on other networks. Each standard offers distinct features tailored to specific use cases, from digital art to in-game assets. The foundation of these standards lies in smart contracts, which are self-executing programs that enforce the rules of token creation, ownership, and transfer.

ERC-721: The Pioneer of Non-Fungible Tokens

ERC-721 is the first standardized interface for non-fungible tokens on Ethereum. Introduced in 2018, it enables the creation of unique digital assets, each with a distinct identifier. This standard ensures that every token is indivisible and non-interchangeable, making it ideal for representing one-of-a-kind items such as digital artwork, collectibles, or real estate deeds. The core functions of ERC-721 include transferFrom, which allows ownership transfer, and ownerOf, which verifies the current holder of a token.

• Implementing ERC-721 requires deploying a smart contract that adheres to the EIP-721 specification.
• Developers must define a name, symbol, and implement event emissions like Transfer and Approval.
• Metadata for each token is typically stored off-chain using IPFS or centralized servers, with a URI returned by the tokenURI function.
• Each token is assigned a unique tokenId, which remains constant for its lifetime.

ERC-721’s structure supports royalty mechanisms through extensions, allowing creators to receive a percentage on secondary sales. However, managing large collections of ERC-721 tokens can be costly due to the need for separate transactions for each token.

ERC-1155: The Multi-Token Standard

ERC-1155 introduces a significant evolution by supporting both fungible and non-fungible tokens within a single contract. Developed by Enjin, this standard allows for batch operations, reducing gas costs and improving efficiency. Unlike ERC-721, where each token requires its own contract or extensive mapping, ERC-1155 uses a single contract to manage multiple token types through a tokenID system that can represent various asset classes.

• A single safeTransferFrom function handles transfers for both NFTs and fungible tokens.
• The balanceOf function can query holdings for multiple token types at once.
• Batch transfers via safeBatchTransferFrom allow moving several tokens in one transaction, drastically cutting gas fees.
• Each tokenID in ERC-1155 can be configured as fungible, non-fungible, or semi-fungible (e.g., limited edition items).

This flexibility makes ERC-1155 ideal for gaming environments where players own a mix of unique weapons, consumable items, and currency. The standard also supports approval for all via setApprovalForAll, enabling third-party platforms to manage a user’s entire inventory.

Other Notable NFT Standards on Ethereum

Beyond ERC-721 and ERC-1155, several experimental or niche standards have emerged to address specific needs. ERC-998, also known as Composable NFTs, allows NFTs to own other NFTs or fungible tokens. This enables hierarchical ownership structures, such as a virtual character (NFT) owning weapons, pets, or tokens.

• ERC-998 contracts implement takeOwnership and transferChild functions to manage nested assets.
• Such composable structures are useful in complex metaverse applications where digital entities accumulate items.

Another emerging standard is ERC-721A, optimized for bulk minting. Created by Azuki, it reduces gas costs when minting multiple NFTs to the same address by updating ownership only once per transaction instead of per token.

• ERC-721A modifies the _mint function to batch updates to the owners mapping.
• It is particularly beneficial for NFT projects offering large public mints.

These variations demonstrate the Ethereum community’s ongoing efforts to refine NFT functionality and reduce user costs.

NFT Standards on Non-Ethereum Blockchains

While Ethereum hosts the most recognized NFT standards, other blockchains have developed their own. On Binance Smart Chain (BSC), BEP-721 and BEP-1155 mirror ERC-721 and ERC-1155 respectively, ensuring cross-chain compatibility for developers familiar with Ethereum standards.

• BEP-721 contracts function identically to ERC-721 but deploy on BSC for lower transaction fees.
• BEP-1155 supports multi-token operations similar to its Ethereum counterpart.

Solana uses a different architectural approach. Its NFTs are built on the Metaplex Standard, which leverages Solana’s token program and stores metadata in separate accounts. NFTs on Solana are typically SPL tokens with a supply of one and metadata linked via on-chain JSON.

• Creating a Solana NFT involves initializing a mint account, token account, and metadata account.
• Metadata includes name, symbol, URI, seller fee basis points, and creators.
• The use of Candy Machine programs enables automated NFT drops with configurable settings.

Tezos employs FA2, a multi-asset standard supporting NFTs, fungible tokens, and allowances in one interface. FA2 emphasizes formal verification and low fees, appealing to artists and institutions.

Choosing the Right NFT Standard for Your Project

Selecting an appropriate NFT standard depends on the project’s requirements. For unique digital art, ERC-721 remains the most trusted option due to its widespread support and proven track record. Projects involving game assets with multiple item types benefit from ERC-1155 due to its efficiency and flexibility.

• If the application requires nested ownership, such as NFTs containing other tokens, ERC-998 should be considered.
• For large-scale mints where cost efficiency is critical, ERC-721A offers substantial gas savings.
• On high-throughput chains like Solana, the Metaplex standard enables fast, low-cost NFT creation suitable for mass adoption.

Developers must also consider wallet and marketplace compatibility. Most platforms support ERC-721 and ERC-1155 natively, while newer or chain-specific standards may have limited integration.

Frequently Asked Questions

Can an ERC-1155 token be both fungible and non-fungible at the same time?Yes, within a single ERC-1155 contract, different tokenIDs can represent different types. One tokenID might represent a non-fungible digital artwork, while another tokenID could represent a fungible in-game currency. The contract manages these distinctions internally.

How is metadata handled in ERC-721 versus ERC-1155?Both standards use a tokenURI function to point to JSON metadata. The structure of the JSON is typically the same—containing fields like name, description, and image. The difference lies in implementation: ERC-721 returns metadata per tokenId, while ERC-1155 can batch metadata queries but usually follows the same URI pattern per token type.

Is it possible to convert an ERC-721 token into an ERC-1155 token?Direct conversion is not possible due to differing contract structures. However, a new ERC-1155 contract can be deployed, and the original ERC-721 token can be burned while minting an equivalent token in the new standard. This process requires user approval and a bridging mechanism.

Do all wallets support ERC-1155 tokens?Not all wallets display ERC-1155 tokens correctly. While major wallets like MetaMask and Trust Wallet have added support, some may only show fungible tokens or fail to render NFTs properly. Users should verify compatibility before transferring ERC-1155 assets.