Async Storage is a community-maintained module for React Native that provides an asynchronous, unencrypted, key-value store. Async Storage is not shared between apps: every app has its own sandbox environment and has no access to data from other apps.
Keychain Services allows you to securely store small chunks of sensitive info for the user. This is an ideal place to store certificates, tokens, passwords, and any other sensitive information that doesn’t belong in Async Storage.
Shared Preferences is the Android equivalent for a persistent key-value data store. Data in Shared Preferences is not encrypted by default, but Encrypted Shared Preferences wraps the Shared Preferences class for Android, and automatically encrypts keys and values.
The Android Keystore system lets you store cryptographic keys in a container to make it more difficult to extract from the device.
In order to use iOS Keychain services or Android Secure Shared Preferences, you can either write a bridge yourself or use a library which wraps them for you and provides a unified API at your own risk. Some libraries to consider: