How to Build a React Native Crypto Wallet: Tools and…

KEY TAKEAWAYS

1. Viem is a ~27–35 kilobyte (minified) TypeScript library that Viem's own published benchmarks show performs Ethereum RPC calls roughly 40 times faster than ethers.js.
2. WalletConnect V2 provides chain-agnostic session management for connecting React Native wallets to decentralized applications across multiple blockchain networks simultaneously.
3. Expo's managed workflow simplifies React Native crypto wallet development but requires manual native module linking for libraries that depend on platform-specific cryptographic code.
4. The public client and wallet client pattern in Viem separates read operations from signing transactions, reducing private key exposure during routine balance and data queries.
5. MetaMask SDK for React Native enables deeplink-based wallet connections that allow users to sign transactions through their existing MetaMask mobile application directly.

  Building a cryptocurrency wallet with React Native requires selecting the right combination of blockchain interaction libraries, key management tools, and connection protocols. The ecosystem shifted significantly in 2025 and 2026 as newer libraries like viem replaced older alternatives with smaller bundles and faster execution.  WalletConnect released its V2 protocol with chain-agnostic session handling, and MetaMask published a dedicated React Native SDK. This article covers the specific tools and libraries needed to build a functional Ethereum wallet in React Native, including setup requirements, architecture patterns, and integration considerations for production deployment.

Core Blockchain Libraries for Ethereum Interaction

Three primary libraries handle Ethereum RPC communication in JavaScript environments: viem, ethers.js, and web3.js. Each provides functions for querying balances, reading smart contracts, sending transactions, and encoding calldata. The differences lie in bundle size, performance, and TypeScript support.Viem ships at approximately 27 to 35 kilobytes minified, according to independent measurements from Dynamic.xyz, BitLauncher, and JamesBachini, compared to approximately 130 kilobytes for ethers.js and a larger footprint for web3.js.Actual bundle sizes vary by configuration, as viem's tree-shakable architecture means unused functions are excluded during compilation. Viem's own documentation benchmarks show it executing common RPC operations approximately 40 times faster than ethers.js.Beyond raw performance, PkgPulse's 2026 comparison notes that the most significant difference is how TypeScript types flow from contract ABIs to application code, providing type-safe contract interactions that ethers.js does not match. The library uses a tree-shakable modular architecture, meaning unused functions are excluded from the final bundle during compilation.Viem separates blockchain interactions into two client types. The public client handles read operations like balance queries and contract state reads without requiring private key access. The wallet client manages transaction signing and requires a connected account with key material. This separation reduces the surface area for private key exposure during routine operations. Ethers.js combines both patterns in its provider and signer abstractions. Web3.js historically used a single Web3 instance for all operations, which was simpler but offered less architectural control over key management boundaries. Web3.js v4 introduced a modular plugin architecture, though its adoption remains behind viem and ethers.js in the React Native ecosystem.For React Native specifically, viem requires a TextEncoder polyfill because the React Native JavaScript engine does not include the Web API by default. Install the text-encoding polyfill and import it before any viem calls in the application entry point.

WalletConnect V2 and External Wallet Integration

WalletConnect V2 is a protocol that establishes encrypted sessions between wallets and decentralized applications across different devices and platforms. The protocol upgrade from V1 to V2 introduced chain-agnostic session management, allowing a single connection to support multiple blockchain networks simultaneously rather than requiring separate sessions per chain.The WalletConnectModal package for React Native provides a prebuilt connection interface that handles QR code generation, deeplink routing, and session persistence. Developers register a project on the WalletConnect Cloud dashboard to obtain a project identifier required for initialization. The modal supports both mobile-to-mobile connections through deeplinks and desktop-to-mobile connections through QR scanning.MetaMask SDK for React Native offers a more targeted integration for applications that want to connect specifically to MetaMask wallets. The SDK uses deeplinks to redirect users to the MetaMask mobile application for transaction signing, then returns the signed result to the calling application. This approach avoids embedding private key management inside the React Native application entirely, delegating all signing operations to MetaMask's audited security infrastructure, as MetaMask documentation confirms.

Expo Setup and Native Module Considerations

Expo's managed workflow provides a streamlined development experience for React Native projects with over-the-air updates, simplified build configuration, and a curated set of prebuilt native modules. However, crypto wallet development often requires native modules that Expo's managed workflow does not include by default.Libraries that depend on platform-specific cryptographic implementations, such as react-native-keychain for secure key storage or react-native-randombytes for cryptographic random number generation, require Expo's development build configuration rather than Expo Go. The Expo documentation explains how to create development builds that include custom native modules while retaining Expo's managed workflow benefits. The recommended project initialization uses the Expo CLI with a TypeScript template. Install viem, WalletConnect, and any required polyfills as npm dependencies. Configure the Metro bundler to resolve Node.js core module replacements using the rn-nodeify package or manual module resolution entries. Testing transaction signing requires a testnet RPC endpoint from providers like Alchemy or Infura configured through environment variables rather than hardcoded values.

Market Outlook

The React Native crypto wallet toolchain continues to mature as libraries like viem gain broader adoption and WalletConnect V2 stabilizes across mobile platforms. Developers should evaluate whether their wallet requires embedded key management or external wallet delegation before selecting their library stack.

FAQs

What is the best library for Ethereum interaction in React Native? Viem is the recommended choice at approximately 27–35 kilobytes minified, with benchmarks showing up to 40 times faster performance than ethers.js and full TypeScript support for type-safe development.Does React Native support WalletConnect V2 for wallet connections? Yes, WalletConnectModal for React Native provides prebuilt QR code and deeplink connection interfaces with chain-agnostic session management across networks.Can Expo be used to build a crypto wallet application? Expo works with development builds that include custom native modules, but Expo Go alone does not support crypto-specific libraries requiring platform-level code.How does the public client and wallet client pattern work? The public client handles read operations without private keys while the wallet client manages transaction signing, reducing key exposure during routine queries.What polyfills does React Native need for view compatibility? React Native requires a TextEncoder polyfill imported before viem initialization because the JavaScript engine lacks the Web API TextEncoder by default.Can MetaMask SDK handle transaction signing in React Native apps? Yes, MetaMask SDK uses deeplinks to redirect signing requests to the MetaMask mobile application and returns signed results without exposing keys.What testnet setup is needed for React Native wallet development? Configure an Ethereum testnet RPC endpoint from Alchemy or Infura through environment variables and use testnet faucets for development transaction testing.

References

1. Viem: TypeScript Interface for Ethereum
2. WalletConnect: WalletConnectModal Documentation
3. MetaMask: React Native SDK Guide
4. Expo: Development Builds Introduction