Chain-Agnostic URI

A Chain-Agnostic URI is a universal resource identifier that specifies a blockchain asset—such as a token, NFT, or smart contract—without being tied to a single blockchain network. It is defined by the Chain Agnostic Improvement Proposal 2 (CAIP-2) standard, which uses a structured format like chain_id:namespace:reference. For example, the URI eip155:1/erc721:0x... identifies an NFT on the Ethereum mainnet. This abstraction allows wallets, explorers, and dApps to interpret and resolve the asset on its native chain, regardless of the interface's current context.

The core innovation is the separation of the chain identifier from the asset identifier. The chain identifier (e.g., eip155:1 for Ethereum) is defined by CAIP-2, while the asset identifier (e.g., erc721:0x... for an NFT) is defined by standards like CAIP-19 and CAIP-22. This two-part structure enables systems to first identify the correct blockchain namespace (like Ethereum or Solana) and then parse the asset details within that context. It solves the critical problem of cross-chain ambiguity where the same contract address can exist on multiple networks.

Chain-Agnostic URIs are foundational for cross-chain interoperability and user experience. They allow a single wallet to display assets from multiple chains using a consistent addressing scheme. Protocols like the WalletConnect protocol and decentralized applications use these URIs to request transactions or permissions without prior knowledge of the user's connected chain. By providing a common language for blockchain resources, they reduce fragmentation and enable the composable, multi-chain ecosystem envisioned by Web3, moving beyond the siloed nature of early blockchain development.

A chain-gnostic URI is a standardized format, often following the caip-10 or caip-19 specifications from the Chain Agnostic Improvement Proposal (CAIP) framework, that encodes an asset's or account's identity independently of any single blockchain. Its core function is to provide a universal identifier that can be resolved to the correct network and address. For example, the URI eip155:1/erc20:0x... specifies the Ethereum Mainnet (chain ID 1) and an ERC-20 token contract, while bip122:000000000019d6689c085ae165831e93/slip44:0 identifies a Bitcoin address. This abstraction allows wallets, explorers, and dApps to understand and interact with resources without prior, hardcoded knowledge of every possible chain.

The mechanism relies on a namespace-system-reference structure. The namespace (e.g., eip155, bip122, cosmos) identifies the blockchain ecosystem or standard. The chain reference (e.g., 1 for Ethereum, osmosis-1 for Osmosis) pinpoints the specific network within that namespace. Finally, an asset or account reference defines the target, such as a token contract address, a native asset denom, or a public key. This structured decomposition allows software to parse the URI, identify the required RPC endpoint, and construct the correct transaction or query. It effectively turns a fragmented multichain landscape into a queryable, unified system.

In practice, a user might share a single chain-agnostic URI for a non-fungible token (NFT), and a supporting wallet would automatically know to connect to the correct chain (like Polygon or Arbitrum) to display or transfer it. This is foundational for cross-chain discovery and interoperability protocols. Developers implement URI resolvers that map the namespace and chain ID to the necessary network parameters—such as the JSON-RPC URL, chain symbol, and block explorer—enabling a consistent user experience. Without this standard, applications would require users to manually switch networks or pre-configure support for each chain individually, creating friction and potential for error.

The adoption of chain-agnostic URIs is critical for the multichain future, reducing infrastructure complexity for developers and simplifying asset management for users. They serve as the backbone for features like universal asset dashboards, cross-chain messaging protocols that need to specify destination chains, and decentralized identity systems that operate across ecosystems. As the standard evolves, it aims to support not just tokens and accounts, but also smart contract functions, specific transaction types, and off-chain data references, creating a truly composable and network-agnostic web3.

A Chain-Agnostic URI is a standardized resource identifier format, such as caip-10:1:0x... or eip155:1/erc721:0x.../123, designed to uniquely and unambiguously reference a blockchain account, asset, or smart contract across any supported network. Unlike a simple Ethereum address, it embeds a Chain ID or Namespace (like eip155 for Ethereum) and an Asset Reference (like a token ID), creating a globally unique identifier that is independent of any single wallet or application's configured network. This solves the critical problem of address ambiguity, where the same hexadecimal string can exist on multiple chains but represent entirely different entities.

The standard is primarily defined by CAIP (Chain Agnostic Improvement Proposals), specifically CAIP-2 for chain IDs and CAIP-10 for account addresses, and is widely adopted by wallets, explorers, and dApps. Its structure typically follows the pattern: namespace:chain_id:address or namespace:chain_id/asset_namespace:asset_address/asset_id. For example, the first CryptoPunk on Ethereum mainnet is eip155:1/erc721:0xb47e3cd837dDF8e4c57F05d70Ab865de6e193BBB/1. This allows any compliant software to parse the URI, identify the target chain (Ethereum Mainnet), and understand the asset type (ERC-721 token #1) without prior configuration or user input.

Key use cases include cross-chain asset discovery, wallet-to-wallet transfers, and dApp interoperability. A user can share a single Chain-Agnostic URI for their NFT, and the recipient's wallet can correctly interpret it regardless of whether it's currently connected to Polygon, Arbitrum, or Ethereum. This eliminates user errors from manual network switching. Furthermore, the standard provides a foundation for universal resolvers that can fetch metadata or state information about the referenced resource by routing the query to the appropriate blockchain's RPC endpoint.

Implementing Chain-Agnostic URIs requires parsers that understand the CAIP syntax and integration with multi-chain RPC providers. For developers, libraries like CAIP-JS facilitate the parsing and construction of these URIs. The move towards this standard represents a significant step in abstracting away blockchain complexity for end-users, enabling a seamless, multi-chain user experience where assets are defined by what they are, not where they happen to be stored. It is a foundational primitive for the emerging chain-agnostic or omnichain application stack.