AvalancheJS is a robust JavaScript library developed in TypeScript to interact with the Avalanche Platform, supporting both browser and Node.js environments. It empowers developers with functionalities such as retrieving address balances, obtaining UTXOs, constructing and signing transactions, and executing signed transactions across the X-Chain, P-Chain, and C-Chain. AvalancheJS also facilitates cross-chain swaps and allows for the addition of validators and delegators, as well as the creation of Subnets and Blockchains. The library requires Node.js LTS version 20.11.1 or higher and can be incorporated into projects via npm or yarn. Developers can access essential modules like avm, pvm, and evm for seamless blockchain operations, employing examples provided for practical implementation.