The app that summarizes your books

Take back control of your book pile.

Over 500 non-fiction book summaries, in 5 minutes. In text or audio. Everything that matters, without the filler.

500+ summaries 5 languages iOS + Android 7 days free

Whether you're hyperactive, overwhelmed by screens, or simply pressed for time, staying focused on a book has become a real challenge. I created Cobalt to simplify our lives: the essence of the best best-sellers, without the fluff, in just 5 minutes! — Théo R. | Founder of Cobalt

Why Cobalt?

A curated library, not another feed to scroll.

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500+ curated summaries

Self-improvement, business, psychology, philosophy, science — the essentials.

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5 minutes per book

The thesis, the reasoning, the key examples. Without the padding.

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Text or audio

Read in the morning, listen on the commute. Pick up where you left off.

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5 languages

English, French, Spanish, German, Italian. One subscription.

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Adjustable depth

Quick overview or detailed summary: adapt it to the time you have.

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7 days free

No-commitment trial. Cancel in one tap if it's not for you.

What our users say

Busy readers who rediscovered the joy of learning.

« I use the app every day on public transport. It's fast and really well made. It's become my main tool for continuous learning. »

Benoit R.

« Exactly what I was looking for! The key concepts are perfect. Being able to adjust the depth of the summaries to my mood — what an incredible comfort. »

Hugo T.

« The concept is brilliant, like Koober but updated and personalized! I wrote to the team about a feature, 10 hours later it was added on a public holiday — I couldn't believe it! 😳🤩 »

Lyrie630..

« Great app to get the essence of a book in a few minutes. I love the summaries by key concept. Honestly, it's really worth it! »

Alice G.