Cobalt
Cobalt: Mobile text and audio summaries with adjustable length and editor-reviewed AI. Ranked #42 of 52 in Book Summary Apps by our editors (4.7/10); pricing: Free plan · 7-day trial; best for mobile readers wanting editor-reviewed AI summaries.
At a glance
- Editor score4.7 / 10
- PricingFree plan · 7-day trial
- Best forMobile readers wanting editor-reviewed AI summaries
- Free planYes
- Facts checked29 Sep 2026
Where it wins
- Read or listen, adjust summary length, and access summaries offline.
- AI-assisted summaries are reviewed by editors and highlight key ideas.
- Scan a book with a phone to look it up and get personalized recommendations.
Where it doesn't
- Available on iOS and Android, with no desktop platform listed.
- The free tier provides selected summary articles on the blog.
- Premium monthly and yearly prices are not published on official pages.
Our verdict on Cobalt
Cobalt turns nonfiction books into short text and audio summaries for readers who want to explore ideas in brief sessions. Its catalog covers personal development, business, psychology, and productivity. The mobile app is available for iOS and Android, and the vendor describes its AI-assisted summaries as reviewed by editors. Adjustable length and highlighted key ideas make the format suited to readers who want either a quick overview or a little more context without reading a full book.
The reading experience centers on summary access and discovery rather than a broad reading platform. Summaries can be saved for offline access, and personalized recommendations help surface material. A phone scan can look up a book, which may be useful when choosing what to explore next. Text and audio are both available, so readers can choose between reading and listening. These features fit mobile use, but Cobalt is positioned for solo readers and its listed platforms are iOS and Android; readers seeking a desktop app should look elsewhere.
Cobalt has a free tier and a seven-day trial. The free tier provides selected summary articles on the blog, while Premium unlocks the full app library and new features. The vendor's official pages do not publish monthly or yearly Premium prices, so buyers should check the app's purchase terms before committing. Cobalt is a fit for mobile readers interested in editor-reviewed AI summaries, offline access, and adjustable formats; it is less suited to people who need desktop access or want to compare a published subscription price first.
Cobalt pricing
Cobalt fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Not verified |
| Catalog size | Not verified |
| Audio summaries | Yes |
| Learning paths | Not verified |
| Notes and highlights | Not verified |
| Offline access | Yes |
| Platform coverage | Mobile |
| Summary languages | Not verified |
| Free trial | 7 days |
| Deployment | Mobile |
| Platforms | iOS, Android |
| Support | |
| Built for | Solo (editorial estimate) |
| Pricing | Free plan · 7-day trial |
| Website | cobaltapp.io |
| Facts checked | 29 Sep 2026 |
Alternatives to Cobalt
- BlinkistA broad summary library with offline listening, learning Guides and an AI add-on.9.8
- ShortformA broad library of analytical book guides with audio, offline access, and reading tools.8.8
- HeadwayGuided summaries with quizzes, spaced repetition, and offline access for mobile learners.7.7
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Reviewed by iTechGuides Editors · Editorial team · Updated Sep 2026
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