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70
BU Score
Strong

KyBook 3 Ebook Reader

4.7 ✍️ Editor
✍️ BU Analytics Review

KyBook 3 Ebook Reader is an iOS app from Konstantin Bukreev in the Food & Drink category, currently rated 4.7★ across 4,508 ratings. Initial signal reads as mixed reviews — supporters praise core features while critics cite stability/value gaps.

Our BU Score puts it at 70Strong (healthy traction). For a Food & Drink app, that means healthy traction.

Track changes month-over-month in the Performance section below — live snapshot history and revenue forecast included.

📊 Performance Tracking LIVE

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idle
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Rating
Reviews
Forecast Revenue / mo
Snapshots tracked
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since first record
Range:

💰 Forecast Revenue / mo

MODEL
Revenue forecast computed from BU's 234 trigger model on each snapshot. Calibrated against ground-truth from 58 verified-revenue apps.
🔬Forecast Breakdown — Why This Estimate?Top 11 of 11 triggers
Our ML model uses 200+ signals from public data. These are the most influential for this app:
Excellent rating (4.7★)METRIC
+$2,200
bugsREVIEW
−$1,800
5 starREVIEW
+$1,800
cancelledREVIEW
−$1,500
excellent appREVIEW
+$1,500
Low install base (4,508 ratings)METRIC
+$1,500
highly recommendREVIEW
+$1,400
slowREVIEW
−$1,200
Established app (7y old)METRIC
+$800
Ad-supported / freemiumMETRIC
+$600
Localized (5 languages)METRIC
+$600
METRIC = structural app data · REVIEW = mined from user reviews · ✓ VERIFIED = Stripe-verified anchor (TrustMRR)

📈 Reviews Growth

LIVE
Cumulative review count from first BU snapshot. Each point = a tracked update.
💚Sentiment Over Time↑ green = positive · ↓ red = negative
Apr 25
May 25
Jun 25
Jul 25
Aug 25
Sep 25
Oct 25
Nov 25
Dec 25
Jan 26
Feb 26
Mar 26

⭐ Rating Trend

LIVE
Average rating evolution. Updates with each new review batch.

🗓️ Snapshot Timeline

HISTORY
Each bar shows a tracked update and the metric delta from the previous snapshot.
App Specs
🔐 Own this app? Claim & verify MRR →
💾 53 MB🔞 17+📱 iOS 11.0+🔖 vv0.7.8🔄 updated 7y ago🌐 CS, EN, RU, ZH, ES📂 Food & Drink💰 Paid🚀 Launched 2018 (7y old)

📝 About this app

KyBook is the application for reading and cataloging e-books in a modern, user-friendly style.

KyBook supports all the major e-book formats, OPDS catalogs and Cloud Storage.

Key features
• All the major e-book formats
• OPDS catalogs
• Comfortable reading mode
• Powerful annotations
• Handy cataloguer
• Cloud Storage

Ebook Formats
• EPub (DRM-free)
• PDF (DRM-free)
• MobiPocket and Kindle (mobi, azw3)
• DjVu
• FictionBook (fb2, fb2.zip)
• Comic Book (cbr, cbz, cbt)
• Audio Book (mp3, m4a, m4b)
• Plain and rich text (txt, rtf)

OPDS Catalogs
• Provides access to enormous collection of free electronic books through OPDS-catalogs support.
• Built-in list of well-known OPDS Catalogs
• Allows add own catalog (e.g. Calibre content server)
• Supports for .onion OPDS Catalogs reachable via Tor Network

Comfortable reading mode
• Themes, color schemes for reading (day, night, sepia and more).
• Page turn with scroll, curl and slide.
• Designed to be fast, energy efficient, optimized for very large books (books in millions of words)
• Auto scrolling mode
• Text-to-speech technology to voice any e-book

EPUB/FB2/MOBI specific features
• Customizable font, text size, page margins, paragraph indentation, background and more
• Typography aware (hanging punctuation, hyphenations and more)

PDF/DJVU specific features
• Crops a page margins in manual and automatic mode
• Smart zooming by double-tap
• PDF Reflow on iPhone
• Page text recognition (OCR)

Powerful annotations
• Marked text and bookmarks
• Drawn annotations in any ebook (Apple Pencil support and just by touching).
• Annotations exports in Markdown, HTML, PDF, RTF formats.

Built-in the summary editor
• Markdown formatting.
• Exports summaries in Markdown, HTML, PDF, RTF formats.

Working with fragments of text
• Translation of separate words or complete sentences in different languages.
• Search for a word definition in dictionaries.
• Custom dictionaries in Dictd, StarDict and Lingvo DSL format
• Full text searching in a book (textual, fuzzy and search using regular expressions).
• Built-in search for a selected text on the Internet or Wikipedia.

Handy cataloguer
• Grouping by categories: by authors, subjects, sequences, publishers, tags, popular, recent, new, unread, reading and finished.
• Tags and collections to categorize ebooks.
• Search for books in the library and anywhere in the Internet.
• Own folders tree and flexible bookshelf settings for layout and sorting.
• Arranging books on a bookshelf by dragging.

Working with a metadata and a table of contents
• Automated extraction of a metadata from ebooks.
• Convenient editing of a metadata.
• Editing and creation (automatic or manual) of a table of contents.

File Storage
• Locally on the device.
• In the Cloud Storage (iCloud Drive, Google Drive, OneDrive, Dropbox, Yandex Disk).
• In the Local network on Shared Folders (SMB/CIFS) or on WebDAV server
• Transparent caching of books in the Internet or Local network.
• Supports of streaming audio books in Cloud Storage.
• Content Server for accessing files on the device via a WiFi.

Synchronization (requires subscription)
• Syncs all ebooks metadata and files.

KyBook offers the following subscriptions options:
• 3 months: 4.49 USD
• 1 year: 14.99 USD

Prices may vary in other countries respecting your local currency exchange rate. Your subscription will be charged to your iTunes account. At the end of the term, unless auto-renewables subscriptions are disabled, your subscription will automatically renew in your iTunes account. You will be charged for the regular price of your subscription within 24 hours prior to the end of the current term. You can turn off automatic renewal in your iTunes account settings at any time, but you must do so at least 24 hours before the end of the current term. Refunds will not be provided for the unused portion of any term.

Terms & Privacy policy
http://kybook-reader.com/terms
http://kybook-reader.com/privacy-policy

🆕 What's New · vv0.7.8

- Fixed the issue with clipped text in PDF Reflow.
- Added the ability to change text size in PDF Reflow mode.
- PDF page is rendered in the current theme when the PDF Reflow mode is on.
- The application now remembers the Reflow mode for the recent open PDF book.
- Various minor improvements and bugfixes.

Profile & Insights

Everything we know — and don't — about this app and its company.

Identification

App name
KyBook 3 Ebook Reader
Developer
Konstantin Bukreev
Bundle ID
com.kolyvan.yar
App Store URL
Open in App Store
Category
Food & Drink
Content rating
17+
Languages
CS, EN, RU, ZH, ES

Company

Website
kybook-reader.com
Tagline
KyBook 3
Description
KyBook Reader for iOS
Founded
Not found
HQ / Address
Not found
Employees
Not found
Logo
Not found

Revenue

Verified revenue / mo
Not found
AI revenue estimate / mo
Not found
AI annual estimate
Not found
ML model estimate / mo
$1.3K/mo
Top-grossing rank
Outside top 100 in US Food & Drink
All-time revenue
Not found
Pricing
Not found

Founder

Name
Not found
X / Twitter
Not found
LinkedIn
Not found
GitHub
http://github.com/kolyvan
X followers
Not found
Public statements
Not found

Funding

Total raised
Not found
Last round
Not found
Investors
Not found
Crunchbase
Not found
AngelList
Not found

Press & Links

Articles found
Not found
Listed on
Not found
Blog
Not found
Press / News
Not found

Contacts & Socials

Socials
github
Email
Not found
Phone
Not found
Contact page
http://kybook-reader.com/help.html
About page
Not found
📈Ratings growth4,508 ratings+28% lifetimeShow 3-year history estimate ▾May 2023Jan 2025May 2026
Tracked (59 weeks) Pre-tracking estimate (35 weeks) · model-based, ±5% noise · anchored to release date and current value
🌍Geographic ReachNot ranked
This app is currently outside the top 100 grossing in all 9 countries we monitor (US, UK, DE, FR, JP, CA, AU, BR, IN). Niche or new apps often launch this way — popularity rankings appear once daily revenue clears the regional threshold.
Profile is built from iTunes Lookup + developer site scrape + ML revenue model. Empty fields show "Not found" — additional sources (Crunchbase, X, IndieHackers, Acquire.com) coming.
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