Web3.js

Web3.js is a JavaScript library for interacting with the Ethereum blockchain and smart contracts from web applications. It provides methods for reading blockchain state, sending transactions, calling contract functions, subscribing to events, and querying account balances and transaction history. The library communicates with Ethereum nodes through JSON-RPC, connecting to providers like MetaMask in the browser or direct node endpoints.

Common use cases in web development include building decentralized application frontends that let users interact with smart contracts, displaying token balances and transaction histories, integrating wallet connection flows, and listening for on-chain events to update the UI in real time. While ethers.js has gained popularity as a lighter alternative with a cleaner API design, Web3.js retains widespread adoption due to its maturity, extensive documentation, and use in many existing tutorials and codebases. For web developers entering blockchain development, understanding either library is essential for building dApp frontends.