Ethers.js vs Viem: Ethereum JavaScript Libraries

Mature & Comprehensive: 7+ years of development with 1M+ weekly npm downloads. Offers a full-featured, object-oriented SDK covering wallets, providers, contracts, and utilities. This matters for prototyping, educational content, and teams needing a single, all-in-one toolkit.

Monolithic Bundle Size: The full library is ~450KB (minified). While modular, tree-shaking is less effective than Viem. This matters for frontend/browser applications where bundle size directly impacts user load times and performance.

Type-Safe & Lightweight: Built with TypeScript-first design, offering superior type inference and a modular architecture. Individual client imports can be < 50KB. This matters for production dApps requiring strict type safety, optimal performance, and fine-grained dependency control.

Lower-Level Abstraction: Requires more boilerplate for common tasks (e.g., wallet connection) and has a steeper initial learning curve. This matters for new developers or projects that prioritize rapid development over ultimate optimization.

• You are building a prototype or MVP quickly.
• Your team is already experienced with its API.
• You need extensive documentation and community examples (45k+ GitHub stars).
• You're writing educational material targeting the widest audience.

• You are building a performance-critical production dApp.
• Your stack is heavily TypeScript-based and benefits from end-to-end type safety.
• You are integrating with a modern framework like Next.js, Nuxt, or SvelteKit.
• You plan to use Wagmi for React hooks (Viem is its native engine).

Monolithic Architecture: The all-in-one design leads to larger client-side bundles, impacting dApp load times. Historical Baggage: While v6 streamlined the API, some patterns (e.g., BigNumber) feel less modern compared to native bigint. Can be overkill for simple, targeted interactions where you only need a subset of functionality.

Conceptual Shift: Its modular, composable design (clients, transports, actions) requires a steeper initial learning curve for developers accustomed to Ethers.js's class-based approach. Ecosystem Maturity: While growing rapidly, it has fewer third-party tutorials, plugins, and Stack Overflow answers compared to the entrenched Ethers.js ecosystem, which can slow down troubleshooting.

Built with TypeScript-first design and ABI-inferred types. This eliminates entire classes of runtime errors (e.g., incorrect argument types) and provides superior IDE autocompletion. This matters for large-scale dApp development and teams prioritizing developer experience and safety.

~30% smaller bundle size and faster execution due to a modular, tree-shakable architecture. Core utilities are ~80kb vs Ethers' ~150kb. This matters for frontend applications where load time directly impacts user retention and for high-frequency operations like wallet connection and signing.

Steeper initial learning curve due to its functional, composable API vs Ethers' class-based OOP. Smaller, though growing, ecosystem with fewer third-party plugins and tutorials. This matters for rapid prototyping or teams with deep, existing Ethers.js expertise.

Battle-tested over 5+ years with massive adoption (used by MetaMask, Uniswap). Extensive documentation and vast community support (4,000+ GitHub stars, 500+ contributors). This matters for mission-critical production systems where stability and available developer talent are paramount.

Comprehensive built-in provider and signer abstractions (JsonRpcProvider, Web3Provider). Simplifies integration with wallets like MetaMask and complex multi-signer setups. This matters for applications requiring broad wallet compatibility without managing low-level RPC details.

Larger bundle size due to monolithic structure and legacy code paths. Some APIs are less ergonomic for modern React/Vue patterns, requiring more boilerplate. This matters for performance-sensitive web apps and teams wanting to adopt a purely functional architecture.