I use Flashcards Deluxe, whose data is only on my phone. After memorizing the password, you can remove the cards. If one is really concerned about security, you

I use Flashcards Deluxe, whose data is only on my phone. After memorizing the password, you can remove the cards. If one is really concerned about security, you can just install a safe password manager and only leave the prompt on the flashcard. For example: [CARD FRONT] What's the password for Service X? [CARD BACK] ( Check answer on 1Password )