Kern — Remember What You Read | Spaced Repetition for Books
For people who finish books<br>Stop forgetting<br>what you read.
You spent ten hours reading that book. A month later, three ideas survive. Kern turns any book you've finished into sharp, swipeable flashcards — then spaced repetition brings the ideas back right as they start to slip.
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★★★★★<br>“Exactly what I was looking for.” Mariom753 · App Store
First two books free · No account · No sign-up
How it works<br>Any book.<br>Just the title.
No uploads, no highlights, no homework. If you finished it — paper, Kindle, audiobook, the one from 2014 — Kern can keep it alive.
Add a book you've read
Type the title. That's the whole job. No EPUBs, no exporting highlights, no note-taking system to maintain.
Get its ideas as cards
Kern writes a deck of original cards from the book's key ideas, examples and surprising claims — like a smart friend telling you the best parts. Ready in seconds.
Swipe five minutes a day
Cards from all your books interleave in one feed. Spaced repetition brings back the ones you're forgetting, right as they start to slip.
The Wall
Every book you add lives on the Wall. Review it and it stays inked. Neglect it and you watch it fade. An honest picture of what's still in your head — no streaks, no guilt trips.
Quick checks
Fast interactive cards that test what actually stuck, not what feels familiar. Recognition is a liar; recall is the receipt.
Original cards, not excerpts
Cards are written from the ideas in original language. Not quotes, not summaries, not a substitute for reading the book.
Private by default
No account, no sign-up, fully offline reviews. Your reading life stays yours.
See it<br>Built to make<br>ideas stick.
Guides<br>Read better.<br>Keep more.
Short, practical guides on making books stick — the science and the system.
Start here<br>How to Remember What You Read
The full system: why highlighting fails, what active recall does, and how to keep a book's ideas for years in five minutes a day.
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The science<br>Why You Forget What You Read
The forgetting curve, explained: what happens to a book in your brain over 30 days, and the one intervention that changes the slope.
Read the guide →
The method<br>Spaced Repetition for Books
How the technique behind Anki and language apps applies to non-fiction books — and why nobody did it until now.
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The shortcut<br>Turn Any Book Into Flashcards
Making book flashcards by hand takes hours per book. Here's how to get a quality deck from just the title, in seconds.
Read the guide →
Audiobooks<br>How to Remember Audiobooks
You can't highlight audio. Why audiobook retention feels worse, and how to keep what you heard without pausing to take notes.
Read the guide →
The comparison<br>Do Book Summary Apps Work?
Summaries compress books you haven't read. Retention tools keep the ones you have. Which problem do you actually have?
Read the guide →
The demo<br>Forty-four seconds,<br>start to finish.
Type a title. Get a deck of sharp cards. Review them on the Wall. That's the whole product — there is no step four.
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FAQ<br>Questions,<br>answered.
How do you remember what you read?<br>The most reliable way is active recall plus spaced repetition: test yourself on a book's key ideas at growing intervals instead of re-reading or highlighting. Kern automates the whole loop — it turns any finished book into recall cards and resurfaces them right before you'd forget. Learn more
Why do I forget books a few weeks after finishing them?<br>Because of the forgetting curve: memory for new information decays exponentially, and most of a book is gone within weeks unless it's retrieved. Passive reading creates recognition, not recall. Spaced review interrupts the curve and moves ideas into long-term memory. Learn more
Does spaced repetition work for books?<br>Yes — spaced repetition is one of the most robust findings in learning science, and it works on book ideas just as well as vocabulary. The hard part was always making the cards; Kern generates them from just the title and schedules the reviews. Learn more
How do I make flashcards from a book without highlights or notes?<br>You don't need highlights. Type the title and Kern builds a deck of original cards from the book's key ideas, examples and surprising claims — written like a smart friend telling you the best parts, not excerpts. Ready in seconds. Learn more
Does Kern work with audiobooks and paper books?<br>Yes. Kern only needs the title, so it works for any book you've finished: paper, library copies, Kindle, audiobooks, even the one you read in 2014. Nothing to import, nothing to sync. Learn more
Is Kern a book summary app like Blinkist or Headway?<br>No. Summary apps compress books you haven't read; Kern makes the books you have read stick. Cards are written from the ideas — not excerpts, not a replacement for reading — and spaced...