web3.js

web3.js is a collection of JavaScript and TypeScript libraries that enable applications to interact with Ethereum and other EVM-compatible blockchain networks. Originally developed by the Ethereum Foundation and maintained by ChainSafe Systems since 2019, web3.js was the first widely-adopted Ethereum JavaScript library and remains one of the most popular, powering the frontend of thousands of decentralized applications (dApps), DeFi protocols, NFT platforms, and cryptocurrency wallets. The library provides a comprehensive abstraction layer over the Ethereum JSON-RPC API, handling the complex details of ABI encoding and decoding, transaction signing, block and transaction retrieval, event log filtering, and smart contract interaction. web3.js is organized into multiple modules: web3-eth (Ethereum blockchain interaction including account management, transaction sending, and block querying), web3-eth-contract (smart contract abstraction for reading state and sending transactions), web3-eth-accounts (account generation, signing, and transaction serialization), web3-net (network information querying), web3-utils (utility functions for hashing, unit conversion, and address formatting), web3-eth-personal (personal account management via the node), and web3-bzz (Swarm decentralized storage integration). Version 4.x (the current major version) introduced significant improvements including a modular package structure (consumers can install only the modules they need for smaller bundles), full TypeScript support with comprehensive type definitions, a plugin system for extensibility, Promise-based API throughout (replacing the older callback-based patterns), and improved error handling. As of 2026, web3.js has over 11,000 GitHub stars.