For people who finish books

Stop forgetting
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.

Download on theApp Store Watch the demo
Kern - Spaced repetition for the books you read | Product Hunt First two books free · No account · No sign-up
Adding a book to Kern by title only — works for paper books, Kindle and audiobooks, no uploads or highlights A Kern recall card testing what actually stuck from Atomic Habits The Wall in Kern — book cards fade when you neglect them and stay inked when you review
How it works

Any book.
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.

1

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.

2

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.

3

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

Built to make
ideas stick.

Kern flashcard from Atomic Habits — spaced repetition card that helps you stop forgetting what you read Adding a book to Kern by title only — works for paper books, Kindle and audiobooks, no uploads or highlights The Wall in Kern — book cards fade when you neglect them and stay inked when you review Quick Check card in Kern testing recall of Atomic Habits — see what actually stuck Kern review feed — flashcards from all your books interleaved in one five-minute daily session Kern card from Unlocking the Universe — no streaks, no guilt, no account, first two books free
App Store reviews

From people who
finished the book.

Real, unedited reviews from the App Store.

So useful!!!

This app is such a great way to get most important points of the books you read! Lessons pulled from them put into easily readable cards! Phenomenal work!

kapza94 · Serbia · App Store

Cool app

Long time ago I had read the book “The Last Lecture”. This app really brought back all memories of it. It was really good book. Thanks Kern for bringing it back.

SM1467 · Croatia · App Store

Great App

This is exactly what I was looking for! This app helped me to remember all the important things from all the books I read.

Mariom753 · Austria · App Store
Guides

Read better.
Keep more.

Short, practical guides on making books stick — the science and the system.

Start here

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.

Read the guide → The science

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

Spaced Repetition for Books

How the technique behind Anki and language apps applies to non-fiction books — and why nobody did it until now.

Read the guide → The shortcut

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

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

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

Forty-four seconds,
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.

FAQ

Questions,
answered.

How do you remember what you read?
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?
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?
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?
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?
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?
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 repetition keeps them in your head. Learn more
How much does Kern cost?
Your first two books are free — no payment, no account. After that, Kern Plus (monthly or yearly) unlocks unlimited books, or unlock a single book with a one-time purchase. Subscriptions renew automatically unless cancelled at least 24 hours before the period ends. Get the app
Do I need an account to use Kern?
No. Kern has no sign-up and no account, and reviews work fully offline. Your reading life stays on your device. Read the privacy policy

Books fade.
Bring them back.

Add the last book you finished. In thirty days you'll still be able to explain it — that's the whole point.

Free to download. Your first two books are free — no payment, no account, no sign-up. Kern Plus unlocks unlimited books, or unlock a single book once and keep it forever.

Download on theApp Store