Features on the Android device
- Open files with .epub extension.
- Customized TOC provided additionally.
- Reopen to the location of last reading page.
- Import .epub eBooks by selecting "Open with" context menu which pops up when you tap .epub file in file browser.
- Import .epub eBooks from the email app's file attachments.
- Choose Options that have one page(landscape) two pages(landscape) or scroll type(portrait) with fixed-layout book and Options that have one page(portrait) or scroll type(portrait) with reflowable-layout book.
- Audio playback and video full screen switch.
- Media Overlay SMIL support to fixed layout ePUB With Read Aloud Feature For Fixed-Layout ePUB.
- Double-tap the image to zoom-in image on the popup.
- Track the path of moving pages.
- To turn pages and toggle menus, use two touches(multi-touch) on both sides and center of the screen, respectively.
- Adjust font size.
- Jump to the reading pages by history buttons.
- Add notes, highlighters or bookmarks of reading pages.
- EPUB reflowable-layout viewer.
- EPUB fixed-layout viewer.
- Select Scrolling type viewer or paging type viewer.
- Browse .epub .zip epub files on your device.
- Find text across all pages of the book.

Features on the iOS device
- Open files with .epub extension.
- Customized TOC provided additionally.
- Import .epub eBooks by selecting "Share with" context menu which pops up when you tap .epub file in file browser iOS built-in app.
- Reopen to the location of last reading page.
- The writing direction of scripts like Korean, English, Japanese, Arabic, etc is used as natural writing direction.
(Reading from-left-to-right, reading from-right-to-left, reading from top to bottom and from right to left; ltr, rtl, vertical-rl)
- EPUB reflowable-layout viewer.
- EPUB fixed-layout viewer.
- HTML5 audio and video playback.
- Media overlay supports synchronizing audio media.
(Option of choosing text element style can be set if media overlay does not have an author-defined style synchronizing audio-text visual highlighting.)
- Adjust text size, line height and margins of content on viewer view.
- Bookmarks, table of contents, memo note.

Features on the Windows device
- Open files with .epub extension.
- Customized TOC provided additionally.
- Reopen to the location of last reading page.
- Import .epub eBooks by selecting "Open with Gglreader" context menu which pops up when you mouse-right-click .epub file in file browser.
- Adjust CSS to change font size, margins, line height
- EPUB reflowable-layout viewer.
- EPUB fixed-layout viewer with one page or two pages.
- Media Overlay SMIL support to fixed layout ePUB With Read Aloud Feature For Fixed-Layout ePUB.
- Browse .epub .zip epub files on your device.

Cautions when using this app
- When you install this Gglreader App.
- There are no pre-imported EPUB eBooks in bookshelf of the Gglreader by default setting.
- Read "Gglreader Manual " which is posted on the Gglreader's main screen to know how to use Gglreader App.