How to Architect for Interoperable Wallet Standards

The modern Web3 ecosystem is a multi-chain reality. Users hold assets on Ethereum, Solana, Arbitrum, and dozens of other networks. A wallet that only supports a single chain, like the original MetaMask with just Ethereum, creates a fragmented user experience. Interoperable wallets solve this by providing a unified interface for managing assets and identities across disparate environments. This requires an architecture designed for extensibility from the ground up, not as an afterthought.

Architecting for interoperability means abstracting away chain-specific details. Instead of hardcoding logic for Ethereum's eth_sendTransaction or Solana's sendAndConfirmTransaction, your wallet core should handle a generic SignRequest object. The architecture must support pluggable providers—modules that translate these generic requests into chain-specific calls. For example, a WalletConnectProvider for EVM chains, a SolanaWeb3Provider for Solana, and a CosmosProvider for Cosmos SDK chains. This design mirrors how browsers use different drivers to render websites.

A critical component is a robust key management layer that is agnostic to the signing algorithm. Whether the user's key is a Secp256k1 private key (Ethereum), an Ed25519 key pair (Solana), or a multisig configuration, the wallet's core should manage them uniformly. This often involves using or extending standards like EIP-4337 Account Abstraction for smart contract wallets or the Wallet Standard for a common interface. The architecture must securely isolate keys while providing a consistent API for signing operations across these different cryptographic systems.

Consider the user experience of adding a new network. In a monolithic wallet, this requires a client update. An interoperable architecture uses a dynamic registry or chain metadata service. The wallet can fetch verified chain information (chain ID, RPC URLs, native currency) from a source like the Chainlist repository or a similar decentralized registry. This allows users to seamlessly connect to new ecosystems without waiting for wallet developers to implement support, future-proofing the application.

Finally, state management becomes complex in a multi-chain context. The architecture needs to track balances, transaction histories, and nonces/sequence numbers for each connected chain simultaneously. Efficiently polling multiple RPC endpoints or indexing services requires a well-designed asynchronous data aggregation layer. This layer should cache data intelligently and update the UI reactively, ensuring performance doesn't degrade as users add more networks. The goal is to make the complexity of a multi-chain world invisible to the end-user.

Interoperable wallet architecture is built on a few foundational standards. The most critical is EIP-6963: Multi Injected Provider Discovery. This standard solves the problem of multiple wallet browser extensions conflicting by providing a standardized discovery mechanism. Instead of applications checking for a single global window.ethereum object, they listen for eip6963:announceProvider events. This allows multiple wallets to coexist, giving users a clear, conflict-free choice. Implementing this is the first step toward a user-centric, multi-wallet environment.

The next layer involves account abstraction and smart accounts, primarily defined by ERC-4337. This standard allows wallets to be smart contract accounts instead of Externally Owned Accounts (EOAs). Smart accounts enable features like social recovery, batch transactions, and gas sponsorship. For architects, this means designing systems where user operations are bundled and relayed through a separate mempool. Understanding the flow—from UserOperation to Bundler to EntryPoint contract—is essential for building applications that leverage this next-generation wallet infrastructure.

A unified interface across different blockchains is achieved through the EIP-1193: Ethereum Provider JavaScript API. This standard defines the request({ method, params }) pattern used by wallets like MetaMask to interact with chains. While originally for Ethereum, its pattern has been adopted by wallets for networks like Polygon and Avalanche. When architecting your dApp, you should use this provider interface abstractly, then use EIP-3085: wallet_addEthereumChain to dynamically inform the wallet about new networks, ensuring your application remains chain-agnostic.

For representing assets and identities across ecosystems, CAIP (Chain Agnostic Improvement Proposals) standards are indispensable. CAIP-2 defines a uniform chain identifier format (e.g., eip155:1 for Ethereum Mainnet). CAIP-10 defines a uniform account address format that includes the chain identifier. CAIP-25 standardizes how wallets report which chains and accounts they currently have enabled. Using these identifiers in your application's state management prevents errors when handling addresses and network contexts from multiple blockchains.

The final architectural consideration is state and session management. Standards like EIP-3085 (for adding networks) and EIP-3326 (for wallet switch Ethereum chain) handle network context. For persistent, permissioned connections, the WalletConnect protocol (v2.0+) provides a secure, remote JSON-RPC bridge via pairing URIs and symmetric keys. Your architecture should separate the wallet connection layer from your core application logic, using these standards to manage network switches, account changes, and session persistence cleanly and predictably.

A modular smart account is a smart contract wallet designed with a pluggable architecture, separating its core logic from its features. Unlike monolithic Externally Owned Accounts (EOAs) or early smart contract wallets, a modular design allows developers to attach, upgrade, and remove modules—discrete pieces of logic for signing, validation, recovery, and spending limits—without redeploying the entire wallet contract. This approach, formalized in standards like ERC-4337 for account abstraction and ERC-6900 for modular accounts, enables interoperability, reduces audit surface area, and future-proofs wallet infrastructure. The core account becomes a lightweight shell that delegates specific actions to authorized modules.

The architecture centers on a clear separation of concerns. The main singleton entry point (defined by ERC-4337) receives user operations. It routes them to the user's account contract, which acts as the core. This account doesn't execute logic directly but validates the operation's signature and permissions by calling into attached validator modules. For execution, it delegates to executor modules. For example, a social recovery module, a session key module, and a multi-signature validator could all be attached to the same account core. This design allows users to mix and match security models and features from different developers, creating a personalized wallet stack.

Implementing this requires a well-defined interface between the core and its modules. The ERC-6900 standard proposes interfaces for IAccountCore, IValidationModule, and IExecutionModule. The core account must maintain a registry of authorized modules and their permissions. When a UserOperation arrives, the core calls validateUserOp on the relevant validator module, passing the operation hash and signature. A pseudo-code snippet for the core's validation might look like:

solidityCopy
function validateUserOp(UserOperation calldata op, address module) internal view {
    require(isModuleEnabled(module), "Module not authorized");
    IValidationModule(module).validateUserOp(op, op.signature);
}

This delegates the cryptographic verification to the specialized module.

Key design considerations include module autonomy vs. core security. While modules handle specific logic, the core must enforce critical invariants: it should manage the module allow-list, handle native token balances, and be the sole entity capable to delegatecall to modules to prevent state corruption. Upgradability is another crucial factor; using immutable module addresses enhances security but reduces flexibility, while a proxy pattern for modules allows updates but adds complexity. Architects must also plan for fallback mechanisms, ensuring a trusted module (like a simple ECDSA validator) remains if a more complex module fails or is deprecated.

For interoperability, adhering to established standards is non-negotiable. Building your account core to comply with ERC-4337 ensures it works with the growing ecosystem of bundlers, paymasters, and alternative mempools. Adopting the interfaces from ERC-6900 ensures your modules can work with other compliant accounts and vice-versa. This standards-based approach prevents vendor lock-in and allows users to compose their wallet from best-in-class components—using a Safe{Core} module for governance, a Biconomy module for gas sponsorship, and a ZeroDev module for passkey authentication, all within a single account contract.

The end goal is a user-centric wallet that is both secure and adaptable. Developers should provide a core account implementation with robust module management and then focus on building specialized, audited modules. The community benefits from a composable ecosystem where innovation happens at the module level, and users are not forced to migrate to new wallet contracts to access new features. This modular paradigm, powered by account abstraction, is foundational for onboarding the next wave of users into Web3 with experiences rivaling traditional web applications.

The Chain Agnostic Improvement Proposal (CAIP) is a set of specifications that standardizes how blockchain networks and assets are identified and referenced. Before CAIP, each wallet or dApp used its own naming conventions (e.g., eth, ethereum, 1), leading to fragmentation and integration complexity. CAIP solves this by defining a universal namespace. The core concept is the CAIP-2 identifier for chains (e.g., eip155:1 for Ethereum Mainnet) and CAIP-10 for account addresses (e.g., eip155:1:0x...). Implementing these standards is the first step toward building truly interoperable applications that can seamlessly interact with users across Ethereum, Cosmos, Polkadot, and other ecosystems.

Architecting your wallet to be chain-agnostic starts with abstracting network and account logic. Instead of hardcoding RPC endpoints or chain IDs, you should design a provider abstraction layer that uses CAIP identifiers as the primary key for all network operations. For example, when a user selects an account, your application should store and reference it as a full CAIP-10 string. This allows you to support a new blockchain simply by adding its CAIP-2 definition and corresponding RPC configuration to your network registry, without changing core account management logic. Libraries like @walletconnect/utils and caip provide helper functions for parsing and validating these identifiers.

A practical implementation involves handling transaction requests. When a dApp sends a transaction proposal via a protocol like WalletConnect v2, it uses CAIP-2 for the chain and CAIP-10 for the from address. Your wallet must parse these identifiers to route the request to the correct blockchain provider. Consider this simplified code snippet for validating a session namespace:

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import { parseChainId } from '@walletconnect/utils';
// A CAIP-2 chainId from a session proposal
const chainId = 'eip155:1';
const parsed = parseChainId(chainId); // { namespace: 'eip155', reference: '1' }
// Use the parsed data to select the correct Ethereum provider
const provider = getProviderForNamespace(parsed.namespace);

This ensures the transaction is signed and broadcast on the intended network.

Beyond basic transactions, CAIP enables advanced interoperability features. The CAIP-25 standard defines a common format for blockchain RPC methods, allowing a dApp to request actions like personal_sign or cosmos_signDirect in a standardized way. Your wallet's architecture should include a method router that maps these CAIP-defined JSON-RPC methods to the appropriate signing library for each namespace. Furthermore, for asset display, use CAIP-19 for asset identifiers (e.g., eip155:1/erc20:0xa0b...) to uniquely represent tokens across chains in user interfaces, preventing confusion between similar tickers on different networks.

Successfully implementing CAIP transforms your wallet from a single-chain tool into a multi-chain gateway. The key architectural takeaways are: abstract all chain-specific logic behind CAIP keys, use established libraries for identifier handling, and design a pluggable provider system. By adopting these standards, you reduce integration overhead for dApp developers, improve user experience by reducing network-switching errors, and future-proof your application for the next wave of blockchain innovation. Start by integrating the CAIP utilities and gradually refactoring your network management code to use these universal identifiers as the source of truth.

Forward compatibility in wallet architecture means designing a system that can seamlessly integrate future standards and protocols without requiring a complete rewrite. The core strategy is abstraction and modularity. Instead of hardcoding support for specific signature schemes or account types, a forward-compatible wallet uses a plugin or module system. This allows new functionalities—like a novel signature algorithm from EIP-3074 or a permission system from ERC-6900—to be added as independent, swappable components. The main wallet logic interacts with these modules through a well-defined interface, insulating the core from constant change.

A critical implementation pattern is the use of an account abstraction entry point. With ERC-4337, user operations are routed through a singleton contract. A forward-compatible wallet client doesn't need to know the internal details of every smart account; it only needs to construct valid user operations and send them to the current entry point address. This decouples the wallet's transaction-building logic from the specific smart contract implementations, allowing users to upgrade their account contracts without changing their wallet app. Libraries like userop.js and frameworks like ZeroDev exemplify this approach.

For interoperability, adopt standardized data formats and RPC methods. The Ethereum Improvement Proposal process defines new JSON-RPC methods (e.g., wallet_switchEthereumChain, wallet_getCallsStatus for ERC-7677). A forward-compatible wallet should implement a middleware layer that can parse requests for known methods and gracefully handle or stub out unknown ones. Similarly, structuring internal data—like transaction requests and signature payloads—according to standards like EIP-712 ensures they can be understood by future tools and other wallets, maintaining cross-application compatibility.

Smart contract wallets must also be designed for upgradeability. Using proxy patterns like the Transparent Proxy or UUPS (EIP-1822) allows the logic of a deployed smart account to be updated. However, forward compatibility requires careful state management; storage layouts must remain consistent, or migration functions must be included. A better strategy is modular smart accounts, as proposed by ERC-6900, where core validation logic is delegated to plug-in modules. This allows new features (social recovery, session keys) to be attached to an account without replacing its core contract, a key strategy for long-lived wallet addresses.

Finally, implement feature detection and progressive enhancement. Your wallet's UI and logic should query connected contracts or the network to discover supported capabilities. For example, before attempting to bundle transactions via a paymaster, check if the account supports ERC-4337 UserOperations. This allows the wallet to offer advanced features when available while providing a functional fallback experience. This strategy ensures users on older standards aren't locked out, while those on new protocols can utilize their full potential, creating a smooth path for ecosystem-wide upgrades.

The key architectural principle is abstraction. By using libraries like wagmi, ethers, or viem with their adapter patterns, you decouple your application logic from any single wallet provider. This approach future-proofs your dApp against new standards like EIP-5792 for multi-chain calls or ERC-4337 for account abstraction, allowing you to integrate them by updating a single adapter layer rather than refactoring core code.

For production systems, rigorous testing across wallet types is non-negotiable. Implement integration tests that simulate connections with MetaMask (EIP-1193), WalletConnect, and embedded wallets like Privy or Dynamic. Use testnets and tools like Hardhat or Foundry to mock different signature formats (e.g., EIP-191 personal_sign vs. EIP-712 typed data). Monitoring user connection analytics can reveal which standards are most used, informing your prioritization for support and optimization.

The interoperability landscape is actively developed. Follow the progress of core proposals on the Ethereum Magicians forum and the official EIPs repository. For implementing specific standards, consult the definitive source: the WalletConnect Documentation for universal linking, the EIP-6963 spec for multi-injection, and the Coinbase Developer Docs for their SDK. Engaging with these communities provides early insight into shifts that will affect your architecture.

Your next practical steps should be: 1) Audit your current dApp for hardcoded wallet assumptions, 2) Choose and integrate an abstraction library, 3) Extend support to at least one new standard (like WalletConnect v2 or EIP-6963), and 4) Establish a testing suite for wallet interactions. This proactive approach ensures your application remains accessible, secure, and competitive as user expectations and technological capabilities continue to advance.