Web3.js v2 (@solana/kit)

The next-generation Solana TypeScript SDK (@solana/kit, formerly @solana/web3.js v2) featuring a modular, functional API. Unlike v1's monolithic classes, v2 uses composable functions and tree-shaking for smaller bundles. Key changes: pipe-based transaction building, codec-based serialization, and native support for versioned transactions. Significantly smaller bundle size than v1.