SideBooks vs 読書尚友
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SideBooks
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.
- Realistic paper curl animation
- Multiple viewing directions
- Enhanced bookshelf management
- Password protection
- Dropbox and iTunes file import
- Supports PDF, ZIP, CBZ, RAR, CBR
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SideBooks is a high performance, high speed PDF viewer that allows you to enjoy reading with the feel of actual paper. =Features= Curl animation that simulates the actual turning of paper pages has been added to the standard page slide function. Supports viewing from 3 directions, documents that open left to right, right to left and vertically. It provides the optimal environment for viewing any book. All zoom rates have been optimized providing high speed, dynamic screen display. An infinite hierarchy of folders can be created, moved, deleted, renamed, etc. using the enhanced bookshelf management function. Real visual bookshelf function that corresponds to back cover style display. Files can be imported by 3 methods, Network transfer through Dropbox, USB transfer through iTunes and direct transfer from other applications. Books can be protected so others cannot view them by using the password protected locking function. This is a universal application that operates on the iPhone, iPod Touch and iPad. =Functions= Overall: *Brightness Adjustment *Screen rotates to match the orientation of the device *Screen Rotation Lock *Password Protected Start-up Lock Viewer: *Support PDF,ZIP,CBZ,RAR and CBR format *Page Turning: Choose from slide or curl *Viewing Directions: Choose from opening left to right / right to left / vertically *Page Spacing: Choose form wide / narrow / none *Facing Pages: Choose the pair of facing pages by setting the cover to on or off *Trim function within the range of page display *Cache pre-read function for the previous and next pages *Set the display for each book and remember the page number of the last page read *Text search function (list display type) *Contents function (also supports hierarchy type) *Bookmark function (with editable memos) *Edit handwritten notes *Send to other applications (Open-In) *Send by email *Printing function (Air Print) *In-page link function *Link to outside URL function (built-in browser / Safari / Printing) *Display / Don't Display link buttons *Page turning function using tap or swipe *Expansion / Contraction function using pinch and double tap (1-1024x zoom) *Viewing of encrypted PDF files with password protection *Display / non-display of statusbar when reading Bookshelf: *Display form: Choose form list bookshelf / visual bookshelf *Function to set theme of visual bookshelf with each folder *Bookshelf thema extension pack (Add-On) *Cover editing function (corresponds to the trim) *File editing function: create, move, delete, setting for all books in folder *Bookmark list *Reading history list *Unread list *Edit of mark choose form already read / unread *Book name search function *Network transfer through Dropbox *USB transfer through iTunes *Direct transfer from other applications Special thanks to, "Give My Regards to Black Jack" SHUHO SATO Manga on Web http://mangaonweb.com
読書尚友
This app is a Japanese vertical text viewer for iOS, offering access to over 10,000 works from Aozora Bunko and supporting local files. It handles various formats and provides customization options for a comfortable reading experience.
- Supports various file formats (text, HTML, PDF, ePub, images, etc.)
- Automatic character code detection
- Browse Aozora Bunko by author, title, genre, and ranking
- Download books directly from Aozora Bunko
- Customizable font, size, background, and page direction
- In-app search and bookmarking
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読書尚友」はiOS 用の日本語縦書きファイルビューアです。青空文庫で公開されている一万冊以上の作品を快適に読書できます。ローカルファイルのビューアとしても利用できます。 ・テキスト、html、PDF、OOXML(.docx)、ODF(.odt)、ePub、htmlz、画像(jpeg, png,bmp)、zip(書庫内のテキストファイルを表示)に対応 ・文字コード自動判定(Shift_JIS,UTF-8,UTF-16) ・作家別・作品別・分野別(NDC)、公開年別の作品リスト、新規公開作品、アクセスランキング ・書き出しの表示 ・青空文庫からのダウンロード ・本棚 ・マーカー ・ローカルファイルの表示 ・作品名の検索 ・青空文庫の主要な注記に対応 ・目次(青空文庫の見出し注記から作成) ・文書内の文字列検索 ・フォントサイズ、フォントの変更 ・背景色・背景画像 ・ページ方向(縦書き・横書き) ・行頭・行末禁則、自動縦中横
Screenshots
Verdict
The clearest difference is rating: SideBooks at 4.6 against 読書尚友's 4.0. SideBooks also leads on ads (none vs shown) and ratings volume (97 vs 1). On price, update cadence, in-app purchases and monetization model there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. SideBooks sells 1 one-off in-app purchase and 読書尚友 sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
SideBooks holds the better App Store score, 4.6 against 4.0. That said, the two scores are not equally well evidenced: SideBooks has 97 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 74% of SideBooks's written reviews are positive against 50% of 読書尚友's.
SideBooks ships an update every 9 days, 読書尚友 every 2 weeks. The most recent releases landed on October 29, 2026 and October 30, 2026 respectively.
| Parameter | SideBooks | 読書尚友 |
|---|---|---|
| Price | Free | Free |
| Rating | 4.6 (97 ratings) — better | 4.0 (1 ratings) |
| Positive reviews | 73.7% of reviews — better | 50.0% of reviews |
| Number of ratings | 97 — better | 1 |
| Update frequency | Every 9 days — better | Every 2 weeks |
| Ads | No — better | Yes |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 | 15.0 |
| Further details — not scored | ||
| Size | 33 MB | 45 MB |
| Age rating | 4+ | 4+ |
| Developer | Tatsumi-system Co., Ltd. | hishida |
Customer experience
SideBooks
読書尚友
Bugs and requests
SideBooks
Reported bugs
3 issues- Crashes when opening certain PDF files
- Corrupted files cause repeated crashes
- Dropbox integration issues on some devices
Requested features
6 requests- 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
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- Implement a more intuitive file management system
読書尚友
Not enough reviews yet to summarise bugs or requests.
In-app purchases
SideBooks
- Thema extension Add-On$0.99
読書尚友
- 広告削除$1.99









