Web3.js

Web3.js is a collection of JavaScript and TypeScript libraries that allow developers to interact with Ethereum-compatible blockchain nodes via HTTP, WebSocket, or IPC connections. Originally developed by the Ethereum Foundation and maintained by ChainSafe Systems since 2021, Web3.js has been the most widely used JavaScript library for Ethereum dApp (decentralized application) development, powering MetaMask, countless DeFi protocols, NFT marketplaces, and Web3 games. Version 4.x (released 2023) is a complete rewrite in TypeScript with modular architecture, improved type safety, and significantly better performance. Key modules include: web3-core (the foundational module with provider abstraction, request managers, and subscription handling), web3-eth (Ethereum blockchain interaction including getBalance, getTransactionCount, getBlock, sendTransaction, sendSignedTransaction, estimateGas, getChainId, and protocol-level RPC calls), web3-eth-contract (smart contract abstraction for deploying, calling, sending transactions, and event listening with automatic ABI encoding and decoding), web3-eth-accounts (wallet management, key generation, transaction signing with EIP-155, message signing, and EIP-712 typed structured data signing), web3-eth-ens (ENS domain resolution and management), web3-net (network information), web3-providers-http/ws/ipc (transport providers), web3-utils (utility functions including unit conversion between Wei and Ether, address validation and checksumming via EIP-55, keccak256 hashing, random hex generation, and BN.js big number support), and web3-validator (runtime type validation for RPC method parameters). The library supports EIP-1193 provider injection (used by browser wallets), JSON-RPC batch requests, and ENS name resolution throughout.