Solana launches v3 of its JavaScript SDK to streamline app development

Solana has shipped version 3 of its JavaScript SDK, and it is the kind of upgrade developers notice in their codebases before anyone notices it on a chart. The release, @solana/web3.js v3, was announced on October 6, 2026, via the @solana_devs account on X. Its pitch is simple: smaller app bundles, cleaner dependencies and one consistent way to build JavaScript apps on Solana. That matters because the SDK sits underneath a huge share of Solana apps. Packages tied to it logged over 3 million downloads in a recent week, so any change here ripples outward fast. What changed in web3.js v3 The SDK rebuilds nine legacy web3.js classes on top of Solana Kit, the newer toolkit Solana introduced in February 2025. The familiar class names stay the same, preserving backward compatibility with established naming. What changed is the plumbing underneath, which now runs on Kit’s more modern foundation. The goal, per the release, is to cut bundle sizes and simplify the dependency structure. The update also aims for consistent interfaces across three core building blocks: signers, clients and codecs. The breaking changes developers need to know Version 3 introduces several breaking changes. Methods...