Viem — TypeScript Interface for Ethereum

Introduction

Viem is a TypeScript-first Ethereum library built by the wevm team (the creators of Wagmi). It takes a composable, tree-shakeable approach where each action is an independent function rather than a method on a large class. Viem replaces ethers.js and web3.js for developers who want strict TypeScript safety and minimal bundle sizes.

What Viem Does

• Reads chain state through a Public Client with actions like getBalance, getBlock, and readContract
• Signs and sends transactions via a Wallet Client connected to a local key or browser wallet
• Encodes and decodes ABI data, function selectors, event logs, and EIP-712 typed data
• Resolves ENS names and supports reverse resolution
• Provides chain definitions for 100+ EVM networks out of the box

Architecture Overview

Viem is organized around three client types: Public Client (read-only RPC calls), Wallet Client (signing and sending transactions), and Test Client (Anvil/Hardhat node manipulation). Each client accepts a chain definition and a transport (HTTP, WebSocket, IPC, or custom). Actions are standalone functions that take a client as the first argument, making them composable and tree-shakeable. ABI types are fully inferred at the TypeScript level, so contract method names, argument types, and return types are checked at compile time.

Self-Hosting & Configuration

• Install with npm install viem and import only the modules you need
• Create clients with createPublicClient or createWalletClient specifying chain and transport
• Use viem/chains to import pre-configured chain objects or define custom ones
• For browser DApps, use custom(window.ethereum) as the transport with a Wallet Client
• Configure batch JSON-RPC via the batch option on the HTTP transport for reduced latency

Key Features

• Full TypeScript inference on contract reads and writes based on ABI literals
• Tree-shakeable architecture keeps production bundles small
• Built-in multicall batching for efficient on-chain reads
• Human-readable ABI support alongside standard JSON ABIs
• Zero dependencies beyond TypeScript types

Comparison with Similar Tools

• ethers.js — Class-based API with a larger footprint; Viem is functional, tree-shakeable, and has stricter types
• web3.js — Plugin-oriented legacy library; Viem offers modern TypeScript ergonomics
• Wagmi — React hooks layer built on Viem; Viem is the framework-agnostic core
• Alloy — Rust equivalent by the same ecosystem; Viem serves the TypeScript/JavaScript side

FAQ

Q: Is Viem a replacement for ethers.js? A: Many teams adopt Viem as a modern alternative. It offers better TypeScript inference and smaller bundles, though ethers.js remains widely used.

Q: Does Viem work in the browser? A: Yes. Viem works in browsers, Node.js, Deno, and Bun with no environment-specific dependencies.

Q: How does ABI type inference work? A: When you pass an ABI as a const assertion, Viem infers function names, argument types, and return types at the TypeScript level, catching errors before runtime.

Q: Can I use Viem without Wagmi? A: Yes. Viem is a standalone library. Wagmi is an optional React/Vue layer built on top of it.

Sources

• https://github.com/wevm/viem
• https://viem.sh