zustand-mmkv-storage: Blazing Fast Persistence for Zustand in React Native

Source: Dev.to

Why Do We Need Persistent State in React Native?

Mobile users expect apps to “remember” them:

• Login tokens should stay valid
• Shopping carts shouldn’t empty on app close
• Theme preferences (dark/light) should persist
• Onboarding flow shouldn’t replay every time

Without persistence, your app feels broken. With good persistence, it feels native and polished.

The Old King: AsyncStorage

For years, AsyncStorage was the default solution. It’s simple, works everywhere, and integrates nicely with libraries like Zustand/Redux.

But it has serious downsides:

• Slow: Fully JavaScript‑based, serialized bridge calls
• Async‑only: Every read/write blocks UI if not careful
• No encryption out of the box
• Deprecated by the React Native core team (replaced by community forks)

Benchmarks show MMKV can be 30–100× faster than AsyncStorage in real‑world scenarios.

Enter MMKV: The Modern Champion

MMKV (Mobile Key‑Value) is a high‑performance key‑value store developed by Tencent and now maintained by Marc Rousavy.

Key advantages:

• Written in C++ with JSI bindings → blazing fast
• Synchronous reads/writes (no await needed for get)
• Built‑in encryption support
• Multi‑process mode (safe for app groups/extensions)
• Tiny footprint, Expo‑compatible
• Actively maintained and used in production by large apps

In short: MMKV is what AsyncStorage should have been in 2025.

Zustand + Persistence = Magic

Zustand is the most popular lightweight state manager in React Native today. Its persist middleware makes saving state trivial — if you have a good storage backend.

That’s where most people hit friction: wiring MMKV manually is verbose, error‑prone, and doesn’t handle instance sharing or encryption cleanly.

Introducing zustand-mmkv-storage

I built zustand-mmkv-storage to solve exactly this.

It’s a tiny wrapper that lets you plug MMKV into Zustand’s persist middleware with minimal boilerplate:

import { create } from 'zustand';
import { persist, createJSONStorage } from 'zustand/middleware';
import { mmkvStorage } from 'zustand-mmkv-storage';

export const useBearStore = create(
  persist(
    (set) => ({
      bears: 0,
      addBear: () => set((state) => ({ bears: state.bears + 1 })),
    }),
    {
      name: 'bear-storage', // key in MMKV
      storage: createJSONStorage(() => mmkvStorage),
    }
  )
);

Your bears count now persists across app restarts — fast and reliably.

Advanced: Encrypted & Isolated Storage

import { createMMKVStorage } from 'zustand-mmkv-storage';

const secureStorage = createMMKVStorage({
  id: 'secure-vault',               // separate file
  encryptionKey: 'my-secret-2025', // enables encryption
});

export const useAuthStore = create(
  persist(
    (set) => ({
      token: '',
      setToken: (token) => set({ token }),
    }),
    {
      name: 'auth-storage',
      storage: createJSONStorage(() => secureStorage),
    }
  )
);

Now your auth token is encrypted on disk and completely isolated from other data.

Use Cases

• Auth tokens & refresh tokens
• User preferences (theme, language)
• Shopping carts / offline forms
• Onboarding completion
• Feature flags / A‑B testing

Try It Today!

npm i zustand-mmkv-storage

GitHub • NPM

If this saves you time or makes your app faster, I’d love a ⭐ on GitHub!

Thanks for reading — happy (and fast) persisting! 🐻✨