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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++
  • ~30x faster than AsyncStorage
  • Uses JSI instead of the "old" Bridge
  • iOS, Android and Web support
  • Easy to use React Hooks API


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


StorageBenchmark compares popular storage libraries against each other by reading a value from storage for 1000 times:

MMKV vs other storage libraries: Reading a value from Storage 1000 times.
Measured in milliseconds on an iPhone 11 Pro, lower is better.


React Native

yarn add react-native-mmkv
cd ios && pod install


expo install react-native-mmkv
expo prebuild


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'

export const storage = new MMKV()

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


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

export const storage = new MMKV({
  id: `user-${userId}-storage`,
  path: `${USER_DIRECTORY}/storage`,
  encryptionKey: 'hunter2'

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. (required if path or encryptionKey fields are specified, otherwise defaults to: '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('user.name', 'Marc')
storage.set('user.age', 21)
storage.set('is-mmkv-fast-asf', true)


const username = storage.getString('user.name') // '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('user.name')

// getting all keys
const keys = storage.getAllKeys() // ['user.name', '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)


// encrypt all data with a private key

// remove encryption


storage.set('someToken', new Uint8Array([1, 100, 255]))
const buffer = storage.getBuffer('someToken')
console.log(buffer) // [1, 100, 255]

Testing with Jest

A mocked MMKV instance is automatically used when testing with Jest, so you will be able to use new MMKV() as per normal in your tests. Refer to example/test/MMKV.test.ts for an example.



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.


Use flipper-plugin-react-native-mmkv to debug your MMKV storage using Flipper. You can also simply console.log an MMKV instance.

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.



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