What is FlutterSecureStorage?
Why Interviewers Ask This
This is a differentiating question used for senior and lead roles. Interviewers want to see if you can explain not just what happens, but why — and what the trade-offs are in different approaches.
Answer
flutter_secure_storage stores sensitive data using the platform's secure storage mechanisms: iOS Keychain and Android Keystore (via EncryptedSharedPreferences on API 23+). Data is encrypted at rest and protected by the device's hardware security module where available. Use it for authentication tokens, refresh tokens, PINs, and passwords — any data that would be a security risk if accessed from a compromised or rooted device. Never use SharedPreferences or Hive for sensitive credentials, as they store data unencrypted.
Pro Tip
If you're unsure about a detail, say so honestly and explain your reasoning. Interviewers respect candidates who can think through uncertainty rather than bluffing.