KOReader is a document viewer primarily targeting e-ink readers. It runs on Cervantes, Kindle, Kobo, PocketBook and Android devices. Developers can also run a KOReader emulator on desktop PCs with Linux or Mac OS X.
Main features for users
- supports multi-format documents including:
- fixed page formats: PDF, DjVu, CBT, and CBZ
- reflowable e-book formats: ePub, fb2, mobi, doc, chm and plain text
- scanned PDF/DjVu documents can also be reflowed with built-in K2pdfopt
- use StarDict dictionaries / Wikipedia to lookup words
- highlights can be exported to Evernote cloud account
- highly customizable reader view and typesetting
- setting arbitrary page margins / line space
- choosing external fonts and styles
- built-in multi-lingual hyphenation dictionaries
- supports adding custom online OPDS catalogs
- calibre integration
- search calibre metadata on your koreader device
- send ebooks from calibre library to your koreader device wirelessly
- browser calibre library and download ebooks via calibre OPDS server
- can share ebooks with other koreader devices wirelessly
- various optimizations for e-ink devices
- paginated menus without animation
- adjustable text contrast
- multi-lingual user interface
- online Over-The-Air software update
Highlights for developers
- frontend written in Lua scripting language
- multi-platform support through a single code-base
- you can help develop KOReader in any editor without compilation
- high runtime efficiency through LuaJIT acceleration
- light-weight self-contained widget toolkit with small memory footprint
- extensible with plugin system
- interfaced backends for documents parsing and rendering
- high quality document backend libraries like MuPDF, DjvuLibre and CREngine
- interacting with frontend via LuaJIT FFI for best performence
- in active development
- with contributions from developers around the world
- continuous integration with CircleCI
- with unit tests (busted), static code analysis (luacheck) and code coverage test (luacov/coveralls)
- automated nightly builds available at http://build.koreader.rocks/download/nightly/
- free as in free speech
- licensed under Affero GPL v3
- all dependencies are free software
Check out the KOReader wiki to learn more about this project.
These instructions for how to get and compile the source are intended for a Linux OS. Windows users are suggested to develop in a Linux VM or use Wubi.
If you only want to work with Lua frontend stuff, you can grab the AppImage and
run it with
To get and compile the source you must have
luarocks installed, as well as a version of
greater than 2.64. You also need
nasm and of course a compiler like
clang. If you want to cross-compile for other architectures, you need a proper
cross-compile toolchain. Your GCC should be at least version 4.8.
Users of Debian and Ubuntu can install the required packages using:
sudo apt-get install build-essential git patch wget unzip \ gettext autoconf automake cmake libtool nasm luarocks \ libssl-dev libffi-dev libsdl2-dev libc6-dev-i386 xutils-dev linux-libc-dev:i386 zlib1g:i386
If you are running Fedora, be sure to install the package
That's all you need to get the emulator up and running with
./kodev build and
Cross compile toolchains are available for Ubuntu users through these commands:
# for Kindle sudo apt-get install gcc-arm-linux-gnueabi g++-arm-linux-gnueabi # for Kobo and Ubuntu touch sudo apt-get install gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf # for Win32 sudo apt-get install gcc-mingw-w64-i686 g++-mingw-w64-i686
block you from building for Kobo or Kindle. Remove them if you get an ld error,
/usr/lib/gcc-cross/arm-linux-gnueabihf/4.8/../../../../arm-linux-gnueabihf/bin/ ld: cannot find -lglib-2.0
NOTE: In the specific case of Kindle & Kobo targets, while we make some effort to support these Linaro/Ubuntu TCs, they do not exactly target the proper devices. While your build will go fine, this may lead to runtime failure. As time goes by, and/or the more bleeding-edge your distro is, the greater the risk for mismatch gets. Thankfully, we have a distribution-agnostic solution for you: koxtoolchain! This will allow you to build the exact same TCs used to build the nightlies, thanks to the magic of crosstool-ng.
On Mac OS X you may need to install the following tools using Homebrew:
brew install nasm binutils libtool autoconf automake cmake makedepend sdl2 firstname.lastname@example.org luarocks gettext pkg-config wget md5sha1sum echo 'export PATH="/usr/local/opt/gettext/bin:$PATH"' >> "$HOME"/.bash_profile
If you run into a gettext error while building glib, try
brew link --force gettext to override the built-in Mac OS BSD gettext with GNU GetText.
Note: in Mojave (10.14) you need to set a minimum deployment version higher than 10.04. Otherwise you'll get the error
ld: library not found for -lgcc_s.10.4.
The KOReader Android build requires
p7zip-full. A compatible version of the Android NDK and SDK will be downloaded automatically by
./kodev build android if no NDK or SDK is provided in environment variables. For that purpose you can use
NDK=/ndk/location SDK=/sdk/location ./kodev build android.
Users of Debian Jessie first need to configure the
sudo echo "deb http://ftp.debian.org/debian jessie-backports main" > /etc/apt/sources.list.d/backports.list sudo apt-get update
For both Ubuntu and Debian, install the packages:
sudo apt-get install ant openjdk-8-jdk
Users on Debian finally need to remove JRE version 7:
sudo apt-get remove openjdk-7-jre-headless
In order to build KOReader package for Ubuntu Touch, the
click package management
tool is needed, Ubuntu users can install it with:
sudo apt-get install click
You might also need SDL library packages if you want to compile and run
KOReader on Linux PC. Fedora users can install
Ubuntu users probably need to install the
Getting the source
git clone https://github.com/koreader/koreader.git cd koreader && ./kodev fetch-thirdparty
Building, Running and Testing
For emulating KOReader on Linux, Windows and Mac OSX
To build an emulator on your current Linux or OSX machine:
If you want to compile the emulator for Windows run:
./kodev build win32
To run KOReader on your development machine:
To automatically set up a number of primarily luarocks-related environment variables:
To run unit tests:
./kodev test base ./kodev test front
To run a specific unit test (for test development):
./kodev test front readerbookmark_spec.lua
NOTE: Extra dependencies for tests:
ansicolors from luarocks.
To run Lua static analysis:
NOTE: Extra dependencies for tests:
luacheck from luarocks
You may need to checkout the circleci config file to setup up
a proper testing environment. Briefly, you need to install
luarocks. The "eng" language data file for
tesseract-ocr is also need to test OCR functionality. Finally, make sure
luajit in your system is at least of version 2.0.2.
You can also specify the size and DPI of the emulator's screen using
-h=X (height), and
-d=X (DPI). There is also a convenience
-s (simulate) flag with some presets like
hidpi. The latter is a fictional device with
--screen_dpi=600 to help ensure DPI scaling works correctly.
./kodev run -s=kobo-aura-one
To use your own koreader-base repo instead of the default one change the
This will be handy if you are developing
koreader-base and you want to test your
modifications with the KOReader frontend. NOTE: this only supports relative path for now.
For EReader devices (kindle, kobo, pocketbook, ubuntu-touch)
To build an installable package for Kindle:
./kodev release kindle
To build an installable package for Kobo:
./kodev release kobo
To build an installable package for PocketBook:
./kodev release pocketbook
To build an installable package for Ubuntu Touch
./kodev release ubuntu-touch
You may checkout our nightlybuild script to see how to build a package from scratch.
For Android devices
A compatible version of the Android NDK and SDK will be downloaded automatically by the
kodev command. If you already have an Android NDK and SDK installed that you would like
to use instead, make sure that the
ndk-build tools can be found in your
PATH environment variable. Additionally, the
SDK variables should point
to the root directory of the Android NDK and SDK respectively.
Then, run this command to build an installable package for Android:
./kodev release android
If your language is not listed on the Transifex project, please don't hesitate to send a language request here.
Variables in translation
Some strings contain variables that should remain unaltered in translation. For example:
The title of the book is %1 and its author is %2.
This might be displayed as:
The title of the book is The Republic and its author is Plato.
To aid localization the variables may be freely positioned:
De auteur van het boek is %2 en de titel is %1.
That would result in:
De auteur van het boek is Plato en de titel is The Republic.
Ccache can speed up recompilation by caching previous compilations and detecting when the same compilation is being repeated. In other words, it will decrease build time when the sources have been built before. Ccache support has been added to KOReader's build system. To install ccache:
- in Ubuntu use:
sudo apt-get install ccache
- in Fedora use:
sudo yum install ccache
- from source:
- download the latest ccache source from http://ccache.samba.org/download.html
- extract the source package in a directory
cdto that directory and use:
./configure && make && sudo make install
- to disable ccache, use
export USE_NO_CCACHE=1before make.
- for more information about ccache, visit: https://ccache.samba.org/