Kern is an iPhone app for people who finish books and then forget them. Type the title of a book you've read (paper, Kindle, library copy or audiobook) and Kern turns it into a deck of cards written in its own words. Non-fiction decks cover the key ideas, examples and surprising claims. Fiction decks revisit the characters, turning points, themes and settings.
Spaced repetition then brings each idea back as it starts to slip, in about five minutes a day, with every book in one mixed feed. Books live on the Wall, staying inked while you review them and fading when you don't. Home Screen and Lock Screen widgets let you answer a card without opening the app, and an optional reminder carries an idea from the book you're losing.
There are no streaks, no leaderboards and no account. Reviews work offline. The first book is free, and Kern Plus unlocks unlimited books.
