axeldelafosse / react-native-mmkv

⚡️ The fastest key/value storage for React Native. ~30x faster than AsyncStorage!

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool


The fastest key/value storage for React Native.

  • MMKV is an efficient, small mobile key-value storage framework developed by WeChat. See Tencent/MMKV for more information
  • react-native-mmkv is a library that allows you to easily use MMKV inside your React Native applications. It provides fast and direct bindings to the native C++ library which are accessible through a simple JS API.


  • Get and set strings, booleans and numbers
  • Fully synchronous calls, no async/await, no Promises, no Bridge.
  • Encryption support (secure storage)
  • Multiple instances support (separate user-data with global data)
  • Customize storage location
  • High performance because everything is written in C++ (even the JS functions have C++ bodies!)
  • ~30x faster than AsyncStorage
  • Uses JSI instead of the "old" Bridge


react-native-mmkv is sponsored by
Try the React Native Chat tutorial 💬


AsyncStorage vs MMKV: Reading a value from Storage 1000 times.
Measured in milliseconds on an iPhone 8, lower is better.


npm install react-native-mmkv


iOS installation is automatic, just run:

cd ios && pod install


To correctly initialize MMKV on Android, please follow the Installation guide.


See this comment for more information: mrousavy/react-native-mmkv#157 (comment).


Create a new instance

To create a new instance of the MMKV storage, use the MMKV constructor. It is recommended that you re-use this instance throughout your entire app instead of creating a new instance each time, so export the storage object.


import { MMKV } from 'react-native-mmkv'

const storage = new MMKV()

This creates a new storage instance using the default MMKV storage ID (mmkv.default).


import { MMKV } from 'react-native-mmkv'

const storage = new MMKV({
  id: `user-${userId}-storage`,
  path: `${USER_DIRECTORY}/storage`,
  encryptionKey: 'some-encryption-key'

This creates a new storage instance using a custom MMKV storage ID. By using a custom storage ID, your storage is separated from the default MMKV storage of your app.

The following values can be configured:

  • id: The MMKV instance's ID. If you want to use multiple instances, use different IDs. For example, you can separte the global app's storage and a logged-in user's storage. (default: 'mmkv.default')
  • path: The MMKV instance's root path. By default, MMKV stores file inside $(Documents)/mmkv/. You can customize MMKV's root directory on MMKV initialization (documentation: iOS / Android)
  • encryptionKey: The MMKV instance's encryption/decryption key. By default, MMKV stores all key-values in plain text on file, relying on iOS's/Android's sandbox to make sure the file is encrypted. Should you worry about information leaking, you can choose to encrypt MMKV. (documentation: iOS / Android)


storage.set('', 'Marc')
storage.set('user.age', 21)
storage.set('is-mmkv-fast-asf', true)


const username = storage.getString('') // 'Marc'
const age = storage.getNumber('user.age') // 21
const isMmkvFastAsf = storage.getBoolean('is-mmkv-fast-asf') // true


// checking if a specific key exists
const hasUsername = storage.contains('')

// getting all keys
const keys = storage.getAllKeys() // ['', 'user.age', 'is-mmkv-fast-asf']

// delete a specific key + value

// delete all keys


const user = {
  username: 'Marc',
  age: 21

// Serialize the object into a JSON string
storage.set('user', JSON.stringify(user))

// Deserialize the JSON string into an object
const jsonUser = storage.getString('user') // { 'username': 'Marc', 'age': 21 }
const userObject = JSON.parse(jsonUser)



As the library uses JSI for synchronous native methods access, remote debugging (e.g. with Chrome) is no longer possible. Instead, you should use Flipper.

Adopting at scale

react-native-mmkv is provided as is, I work on it in my free time.

If you're integrating react-native-mmkv in a production app, consider funding this project and contact me to receive premium enterprise support, help with issues, prioritize bugfixes, request features, help at integrating react-native-mmkv, and more.


See the contributing guide to learn how to contribute to the repository and the development workflow.




⚡️ The fastest key/value storage for React Native. ~30x faster than AsyncStorage!



Language:Objective-C++ 30.3%Language:C++ 25.2%Language:TypeScript 23.1%Language:Objective-C 8.5%Language:Java 6.0%Language:Ruby 2.6%Language:JavaScript 2.2%Language:CMake 1.8%Language:C 0.2%Language:Swift 0.1%