Excellent Utilities: KOReader – versatile document viewer

Last Updated on January 6, 2023

In Operation

The software has 2 interfaces consisting of a reading screen and a file browser. The most important thing to learn about the reading screen is where to tap/click. This is neatly illustrated in the user guide. We’ve reproduced the relevant page below.

KOReader - reading screen

It’s worth reading the user manual as it’s well written and structured.

The software supports a wide range of formats including fixed layout documents such as PDF, DjVu and images. It also supports reflowable documents such as EPUB, HTML, DOCX, RFT, TXT, CHM, and others. There’s also support for ZIP files.

Other features include:

  • Dictionary integration in EPUB and scanned PDF and DjVu documents.
  • Wikipedia lookups.
  • Define custom margins.
  • Set your own fonts (TrueType and OpenType formats), change the size, formats, invert, and other formatting options.
  • Sync with Calibre to manage your ebooks.
  • Different ways to traverse through documents:
    • Skim widget.
    • Book map – provides a useful overview of a book. It can show which parts of the book you have already read, and more.
    • Page browser.
  • Night mode.
  • Bookmarks.
  • Autoturn.
  • News downloader (RSS/Atom).
  • Define Custom DPI to change the size of the interface.
  • Bottom bar offering tons of customization.
  • Two methods of highlighting text – normal highlight mode, and select and highlight mode. Export highlights with a plugin or external program.
  • Plugins.
  • Internationalization support


KOReader is a wonderfully responsive document reader. It’s fast, brimming with features, and highly customizable. The fact that it supports a wide variety of devices is the icing on the cake.

While it faces stiff competition in the document viewer category, it earns our strong recommendation.

It’s a welcome addition to our Excellent Utilities feature.

Website: koreader.rocks
Support: User Guide, Wiki, GitHub Code Repository
License: GNU Affero General Public License v3.0

KOReader is written in Lua. Learn Lua with our recommended free books and free tutorials.

Pages in this article:
Page 1 – Introduction / Installation
Page 2 – In Operation / Summary

Complete list of articles in this series:

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