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,
• 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

What’s New

Version v0.7.8

- 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.

Ratings and Reviews

4.5 out of 5
364 Ratings

364 Ratings

Julo Satran ,

Probably the best multiformat reader avaible

It good, reliable and easy to use and the OPDS makes it the easiest to connect to commercial and private/personal libraries. The developer answers are sometimes hard to read (and may seem rude) but that is mostly a language issue.
Some of the developer decisions are of questionable value - e.g., books wrongly labelled as iso1 when they should be labelled unicode8 are not displayed well on kybook while the Apple books app displays them well - and refusing the use of heuristics when others use them - made me to spend some time and effort to relabel some/many old books (with scripts) that where all usable in other readers. The decision to monetize by charging for sync through a subscription is understandable (the developer has to make a living too) but I am not sure it is wisest.

NebraskaJer ,

Was a great app

Version 2 was great, awesome, unique and a must install. Now version 3 and not much has changed but a new pricing model. Why??!??? I paid lads than three months ago and would not mind to upgrade to version 3. Show me the benefits and what is better about. Why not have a discount for version 2 holders? Then on top of that you have a subscription mode? Why do you give me a pro “upgrade” model and then ask for subscription? Ugh. Did Adobe or Microsoft buy you or something. Another day another app that wants to jump on the SAAS model. Very unhappy. I guess I will convert all mobi and epub to pdf or just import into iBooks. Another app down the tube. What is the point of a “subscription” model for this? I understand making some money and keeping it updated so charge me a flat fee. I use it once a month or so, so I am not doing the rolling subscription. Uninstalling and keeping version 2 until a response is heard or you roll back on the decision. I have a cloud subscription for iCloud so why can’t I download and sync with that? I have all my ebooks there already and would love it to see your team utilize iCloud fully. Why get in the business of making a book storage server? Apple and Google can do it way better and cheaper. Please rethink this and stick to what you are good at. Creating a book reader. If this continues I hope Apple buys this app and rolls it into iBooks. Win-win for me. Thanks anyway.

cunningjames ,

Reads nearly anything and does it pretty darned well

I purchased this in order to read djvu files, which is an unfortunately obscure format. But I find myself turning to this to read PDFs and ebooks as well — it’s attractive and fast and customizable.

I have one quibble; the library and collections interface is a little confusing. But that’s not really the most important part of a reader anyway.

Also, I once asked the developer for something (to remove the home bar indicator on the iPhone X and up). I interpreted his response as a snarky dismissal, but it was hardly a week later before that enhancement showed up in the app. So mea culpa there.


Konstantin Bukreev
55.9 MB

Requires iOS 11.0 or later. Compatible with iPhone, iPad, and iPod touch.


English, Czech, Russian, Simplified Chinese, Spanish

Age Rating
You must be at least 17 years old to download this app.
Unrestricted Web Access
Infrequent/Mild Horror/Fear Themes
© Konstantin Bukreev
In-App Purchases
  1. Upgrade to Pro $4.99
  2. Upgrade to Pro (Discount) $2.99
  3. Yearly subscription $14.99


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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