RMRK Standard

The RMRK Standard is a suite of open-source, on-chain specifications that extend the functionality of non-fungible tokens (NFTs) beyond static images. It introduces a set of legos—composable primitives—that allow NFTs to own other NFTs (nesting), equip other NFTs as wearables or components (equippables), react to on-chain conditions (conditional rendering), and be governed by decentralized autonomous organizations (DAOs). Developed natively for the Kusama and Polkadot blockchains, its architecture is designed to be chain-agnostic, enabling sophisticated, multi-resource, and interactive digital objects.

At its core, RMRK solves the composability problem in traditional NFT systems. Through its Nesting lego, an NFT (like a virtual land parcel) can contain other NFTs (like buildings or avatars). The Equippable lego allows an NFT (e.g., a character) to equip other NFTs (e.g., a sword or armor) from different collections, creating complex, layered assets. These interactions are governed entirely on-chain without relying on centralized servers, making the system trustless and interoperable. This framework is foundational for building complex metaverses, advanced gaming items, and dynamic digital art.

A key innovation is the concept of Multi-resource NFTs. A single NFT token can have multiple representations (e.g., a 3D model, a 2D image, and an audio file), with the displayed resource changing based on context or the viewer's device. Combined with Conditional Rendering, an NFT's appearance or behavior can automatically update in response to on-chain events, time, or the holder's other assets. This turns NFTs from static collectibles into reactive and context-aware applications, enabling use cases like evolving artwork, game items that level up, or identity badges that update with achievements.

The standard is implemented through a system of RMRK pallets (Substrate runtime modules) and a set of smart contracts (RMRK 2.0) for EVM-compatible chains. Its on-chain catalog acts as a registry for approved collections and schemas, ensuring interoperability and security for equippable components. By building a rich, relational graph of assets on-chain, RMRK provides the infrastructure for truly decentralized and user-owned digital worlds, where complex assets can be composed, traded, and interacted with across different applications without vendor lock-in.

RMRK is an acronym for Remark, a term chosen for its dual meaning in English and its technical function within the blockchain. In common parlance, a 'remark' is a comment or annotation. In computing, a 'REMARK' statement is a non-executable line of code used for documentation. This duality perfectly encapsulates the protocol's purpose: it is a system for attaching complex, executable metadata—or 'remarks'—to on-chain assets like NFTs, thereby documenting and enhancing them without modifying their core token contract.

The standard was conceived and developed primarily by Bruno Škvorc and the team at RMRK.app, emerging from the unique constraints and opportunities of the Kusama and Polkadot networks. Unlike Ethereum, these chains emphasize minimal on-chain data storage for efficiency. RMRK was invented as a novel solution to this constraint, using the system.remark extrinsic—a generic, low-cost function for storing arbitrary data—as its foundational primitive. This origin story makes RMRK a native, chain-agnostic Lego protocol built for and from the Substrate ecosystem.

The evolution of the name is also reflected in its versioning. The initial implementation, RMRK 1.0 or 'RMRK Legacy,' established concepts like nested and equippable NFTs. Its successor, RMRK 2.0, rebranded the acronym to stand for ReMaR****Kable, signaling a more ambitious scope. This iteration introduced the idea of NFTs as decentralized applications (NFTs as apps) and abstracted the system into a set of modular pallets. The name thus evolved from describing a simple action (to remark) to describing the outcome: creating remarkably complex and composable digital objects.

The RMRK standard is a set of NFT primitives built on the Kusama and Polkadot ecosystems that enables complex, composable, and context-aware digital assets. Often described as "NFT 2.0," its core innovation is treating NFTs like LEGO bricks—individual components that can be combined and recombined to form more sophisticated systems. This is achieved through a series of custom implementations of the ERC-721 and ERC-1155 standards, adding new functionalities directly on-chain without requiring smart contracts for every new feature.

RMRK's functionality is built on several key legos or primitives. Nesting allows an NFT to contain other NFTs, such as a character backpack holding items. Equipping lets an NFT grant specific slots (e.g., head, hand) that can be filled by other compatible NFTs, governed by rulesets. Multi-resource NFTs can have multiple representations (e.g., 2D image, 3D model, music) that are displayed based on the context or platform. On-chain emotes allow users to react to NFTs, and conditional rendering changes an NFT's appearance based on the items it has equipped or owns.

This composability unlocks profound use cases. A simple example is an avatar NFT that can equip wearable NFTs from different collections, changing its visual appearance and attributes. More complex systems include composable gaming ecosystems, where a land NFT can nest building NFTs, which in turn contain item and character NFTs, all forming a single, tradable entity. It enables fractionalized and delegated ownership, where different NFTs within a nested hierarchy can be owned by different people, facilitating collaborative asset creation and management.

From a technical perspective, RMRK implements these features through a system of on-chain remarks. Instead of storing bulky data, NFTs contain structured notes in their metadata that reference other NFTs and define their relationships. This keeps the chain lightweight while maintaining a verifiable and immutable record of composition. The standard is designed to be chain-agnostic in principle, though its primary deployment and tooling are focused on the Kusama Relay Chain via the Singular platform and other parachains in the Polkadot ecosystem.

The LEGO principle fundamentally shifts NFTs from static collectibles to interactive systems. It moves the logic from the smart contract level to the NFT metadata level, allowing for infinite recombinability without developer intervention. This creates a foundation for user-driven ecosystems, persistent metaverse assets, and complex digital economies where value and function are layered and composable across different applications and virtual worlds.

The RMRK 1.0 standard, launched in 2021, introduced foundational concepts for NFTs on Kusama that went beyond simple collectibles. Its core innovations were nesting (allowing NFTs to own other NFTs), equipping (letting NFT assets be equipped into other NFTs, like a sword into a character), and multi-resource support (enabling a single NFT to have multiple representations, such as a 3D model, an image, and a music file). These features established RMRK as a pioneer in what it termed "legos for NFTs," enabling complex, interactive digital objects.

Building on this foundation, RMRK 2.0 (also known as RMRK Legacy) was a major architectural overhaul that formalized and expanded these concepts into a more robust and interoperable system. It introduced a clear specification with defined interaction rules and a schema for data organization. Key advancements included conditional rendering (where an NFT's displayed resource changes based on context or equipped items), fractionalization of NFTs, and on-chain emotes (reactions). This version solidified the concept of NFTs as complex, stateful systems rather than static tokens.

The evolution from RMRK 1.0 to 2.0 represented a shift from experimental features to a production-ready, EVM-compatible standard. While 1.0 proved the viability of composable NFTs on a parachain, 2.0 provided the rigorous framework necessary for scalable application development. This paved the way for the subsequent RMRK 3.0 (Singular), which further abstracted the logic into a pallets-based system for the Polkadot SDK, but the core principles of nesting, equipping, and multi-resource assets defined in the 1.0-to-2.0 journey remain the protocol's defining contribution to the NFT ecosystem.