# SideBooks vs KyBook

The clearest difference is rating: SideBooks at 4.7 against KyBook's 4.4. SideBooks also leads on update cadence (every 9 days vs every 3 weeks). KyBook's advantage is ratings volume (466 vs 98) and iOS requirement (8.0 vs 15.0). On price, review sentiment, ads and in-app purchases there is nothing between them.

Both are free to download. SideBooks sells 1 one-off in-app purchase and KyBook sells 2 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.

SideBooks holds the better App Store score, 4.7 against 4.4. Both are backed by a comparable volume of ratings — 98 and 466 respectively. Written reviews point the same way: 74% of SideBooks's written reviews are positive against 71% of KyBook's.

SideBooks ships an update every 9 days, KyBook every 3 weeks. The most recent releases landed on November 8, 2026 and November 6, 2026 respectively.

## The numbers

| Metric | SideBooks | KyBook |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (98 ratings)](https://appshunter.io/ios/app/sidebooks/id409777225/reviews)** | [4.4 (466 ratings)](https://appshunter.io/ios/app/kybook-epubfb2pdfdjvu-reader/id673027171/reviews) |
| Number of ratings | 98 | **466** |
| Positive reviews | **73.8% of reviews** | 71.2% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 9 days** | Every 3 weeks |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 33 MB | 50 MB |
| Requires iOS | 15.0 | **8.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Tatsumi-system Co., Ltd.](https://appshunter.io/developer/409777230) | [Konstantin Bukreev](https://appshunter.io/developer/547576207) |

## What reviewers say

### SideBooks

[App page](https://appshunter.io/ios/app/sidebooks/id409777225)

This app offers a high-performance PDF and comic viewer with realistic paper-turning animations. It supports various viewing directions, enhanced bookshelf management, and secure password protection for your documents. Easily import files from multiple sources and enjoy a customizable reading experience.

**Highlights:** Realistic paper curl animation, Multiple viewing directions, Enhanced bookshelf management, Password protection, Dropbox and iTunes file import, Supports PDF, ZIP, CBZ, RAR, CBR

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Thema extension Add-On | $0.99 | one-time |

**What reviewers like**

- 🚀 Smooth page turning
- 📚 Great for reading comics and manga
- 🗂️ Excellent folder organization
- 🔍 Useful search and table of contents features
- 💻 Seamless Dropbox integration

**What reviewers complain about**

- 🐛 Crashes when loading large files
- 🚫 Limited file format support (no CBZ/CBR)
- 🔍 Difficult to find and delete books
- 🔒 Requires Dropbox access, no local file support
- 🔍 Small thumbnail size makes it hard to browse

**Reported bugs**

- Crashes when opening certain PDF files
- Corrupted files cause repeated crashes
- Dropbox integration issues on some devices

**Requested features**

- Add support for ePub and other popular formats
- Implement iCloud/Google Drive integration
- Allow manual rearrangement of bookshelf
- Add dark mode and customizable background options
- Improve bookmark and annotation features


### KyBook

[App page](https://appshunter.io/ios/app/kybook-epubfb2pdfdjvu-reader/id673027171)

This app is a versatile e-book reader supporting a wide range of formats including EPUB, PDF, and audiobooks. It offers extensive customization for reading modes, cloud storage integration, and easy book organization. Advanced features like DJVU support and speed reading are available via in-app purchase.

**Highlights:** Supports EPUB, FB2, PDF, DJVU, CBR, CBZ, MP3, M4A, M4B formats, OPDS catalogs and cloud storage integration, Customizable reading mode settings, Book organization and cataloging, Text-to-speech and dictionary support, Speed Reading (RSVP)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Upgrade to Pro Version | $0.99 | one-time |
| Upgrade to Pro Version | $1.99 | one-time |

**What reviewers like**

- 👍 Easy to use
- 🚀 Fast and smooth performance
- 📚 Supports wide range of file formats
- 🔖 Good organization and categorization features
- 🔊 Excellent text-to-speech functionality

**What reviewers complain about**

- 🐛 Syncing issues, especially with Dropbox and Google Drive
- 🔍 Navigation and file management could be improved
- 💰 Paid version required for some key features
- 📢 Intrusive ads in free version
- 🔧 Lack of updates and support from developers

**Reported bugs**

- Crashes after recent iOS updates
- Text-to-speech function not working properly on newer devices
- Inability to delete books from the app
- Inconsistent theme and color customization behavior

**Requested features**

- Add support for more languages
- Improve image handling and layout
- Implement better annotation and highlighting tools
- Provide easier access to main library from subfolders
- Add ability to password protect individual books or folders


## Frequently asked questions

### Is SideBooks free?

SideBooks is free to download, with in-app purchases available.

### Is KyBook free?

KyBook is free to download, with in-app purchases available.

### Which has better reviews, SideBooks or KyBook?

SideBooks is rated higher. SideBooks averages 4.7 out of 5 from 98 ratings, while KyBook averages 4.4 from 466 ratings.

### Do SideBooks or KyBook have ads?

Neither SideBooks nor KyBook shows ads.

### Which is updated more often, SideBooks or KyBook?

SideBooks ships an update every 9 days, and KyBook every 3 weeks. Most recently, SideBooks was updated on November 8, 2026 and KyBook on November 6, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*