Originally published on NextFuture Picking a state library in 2026 is no longer a religious war. It is a budget question. Bundle bytes are billed against your LCP. Boilerplate is billed against your team's velocity. Here is how Zustand and Redux Toolkit actually compare on the eight things that matter once you ship to production. If you want the broader landscape — Jotai, Valtio, TanStack Query, signals — read our complete React state management guide first. TL;DR New project? Pick Zustand. Smaller bundle, less ceremony, ergonomic with TypeScript and React 19. Existing RTK + RTK Query app with experienced team? Stay. Migration cost rarely beats the tax of dual paradigms. Need time-travel debugging or strict event-sourced patterns? Redux still wins. 1. Bundle size The honest comparison is zustand vs @reduxjs/toolkit + react-redux , because nobody ships hand-rolled Redux anymore. Zustand 4.5.x: ~3-4kb gzipped, zero peer deps beyond React.…