What are the differences between Keychain and UserDefaults?

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TL/DR

UserDefaults and Keychain are both useful in storing small key-value pairs on the user's device, but their security capabilities differ greatly.

Keychain is the only native option for storing data on an iOS device in an encrypted manner.

It's typically meant for storing small amounts of data like an access token, credentials, or other sensitive information. However, while it is still the most secure offering on iOS, it’s important to know that Keychain data can be accessed on jailbroken devices.

Since Keychain is implemented as an SQLite database stored on the file system, it is slower than UserDefaults. Lastly, values stored in the Keychain will persist across application deletions and re-installs unless explicitly deleted.

UserDefaults also allows you to store key-value pairs across different invocations of your app, but it is not secure.

Values stored in UserDefaults are eventually written to a .plist file which are entirely human-readable.UserDefaults are usually used to store basic key-value pairs and user preferences. If you don't need the Keychain's security features, UserDefaults are the more convenient choice. Finally, unlike in the Keychain,items saved in UserDefaults will not persist across application deletions and re-installs.