kernKern, for
the record.
Everything you need to write about Kern: description, fact sheet, screenshots, icon and developer bio. For anything else — interviews, promo codes, TestFlight builds — email hello@kern.cards.
Download full press kit (.zip, 2.4 MB)One paragraph
Kern is an iOS app for people who finish books and lose them. Type the title of any book you've read — paper, Kindle, library copy or audiobook — and Kern turns it into a deck of sharp, swipeable cards: the key ideas, examples and surprising claims, written in original language like a smart friend telling you the best parts. Spaced repetition then resurfaces the ideas right as they start to slip, five minutes a day, with every book in one interleaved feed. Books live on the Wall, staying inked while you review and visibly fading when you don't — no streaks, no leaderboards, no account. The first two books are free; Kern Plus unlocks unlimited books.
A quote you can use
"I kept finishing books I loved, and six months later I couldn't explain them. Summary apps compress books you haven't read — nobody was solving the opposite problem: keeping the ones you have. So I built the tool I wanted: type the title, get the ideas back five minutes a day."
— Josip Petric, developer of Kern
Why this is
a story
The anti-streak app
In a market built on streaks, badges and guilt, Kern refuses all of it. Books visibly fade when neglected and get re-inked when reviewed — an honest picture instead of a dopamine loop.
No account, fully offline
No sign-up, no email capture, no cloud profile. In 2026 that's a product decision worth writing about: your reading life stays on your device.
Works for the forgotten formats
Audiobooks, paper books, library copies, the book you read in 2014 — every retention tool demands highlights or uploads. Kern needs a title. That covers the majority of most people's libraries that no other app touches.
Built solo in Slavonia
One developer in Požega, Croatia, with 14 years of iOS experience — shipping alone against VC-backed reading apps, with seven solo releases to his name.
The details
- Name
- Kern
- Tagline
- Stop forgetting what you read.
- Platform
- iOS (iPhone), native Swift
- Category
- Education / Reading
- Pricing
- Free (first two books) · Kern Plus subscription or one-time single-book unlock
- Privacy
- No account, no sign-up; reviews work fully offline
- Website
- kern.cards
- App Store
- Download on the App Store
- Developer
- Josip Petric, independent developer — Požega, Croatia
- Contact
- hello@kern.cards · @JoPetric
Screens
Full resolution 1242 × 2688 PNG. Click any image to download.
About Josip
Kern is built by Josip Petric, an iOS engineer from Požega, Croatia, with 14 years of experience — by day building IoT apps used by tens of thousands of people, on top of years of client work through Toptal across apps of every kind. The rest of the time he ships his own: Kern is his seventh solo release, following the survival game Last Echo.
He built Kern for a simple reason: he kept finishing non-fiction books and, six months later, couldn't explain them. Highlighting didn't fix it and summary apps solved a different problem, so he built the tool he wanted — one that assumes you actually read the book, and makes sure the ten hours you spent on it aren't quietly erased.
Press photo: download · Reach him at hello@kern.cards or @JoPetric
Writing about Kern?
Happy to help with promo codes, extra assets, or answers to anything. One email away.
hello@kern.cards