KoReader
A document viewer and ebook reader optimized for e-ink devices, supporting PDF, EPUB, DjVu, and many other formats.
What is KoReader?
KOReader is a document viewer and ebook reader application designed primarily for e-ink devices like Kindle, Kobo, and PocketBook, but also runs on Android and Linux. It supports a wide range of formats including PDF, EPUB, DjVu, and FB2, and offers a highly customizable reading interface with features like multi-lingual hyphenation, dictionary lookups, and integration with calibre and other content providers.
Users of e-ink readers (Kindle, Kobo, PocketBook, reMarkable, etc.) who want a more powerful, customizable reading experience than the built-in software, as well as Android and Linux users seeking a feature-rich, open-source document viewer.
Developers and users choose KOReader for its exceptional e-ink optimization, extensive format support, and deep customization options—all in a fast, open-source package that integrates seamlessly with popular tools like calibre and Wikipedia.
Overview
An ebook reader application supporting PDF, DjVu, EPUB, FB2 and many more formats, running on Cervantes, Kindle, Kobo, PocketBook and Android devices
Use Cases
Best For
- Reading PDF and EPUB files on e-ink devices with custom typography
- Managing a personal ebook library with calibre integration
- Looking up words and definitions directly within ebooks
- Reading scanned PDFs with reflow capabilities
- Customizing reading margins, fonts, and spacing on e-ink readers
- Accessing online content like Wikipedia and RSS feeds from an e-reader
Not Ideal For
- Users wanting a polished, commercial-grade reading app with seamless cloud sync and dedicated customer support
- Projects requiring native support for iOS or Windows operating systems
- Casual readers who prefer a simple, intuitive interface without extensive customization options
- Teams needing tight integration with proprietary ebook stores like Amazon Kindle Store or Apple Books
Pros & Cons
Pros
Handles over a dozen formats including PDF, EPUB, DjVu, and even scanned PDF reflow using K2pdfopt, as listed in the multi-format documents feature.
Custom UI without animation, paginated menus, and adjustable text contrast specifically tailored for e-ink displays, leading to faster page turns measured on older devices.
Allows setting arbitrary margins, line spacing, external fonts, and bundled hyphenation dictionaries for a personalized reading experience, detailed in the full-featured reading section.
Integrates with calibre for metadata and wireless transfer, plus Wallabag, Wikipedia, and OPDS catalogs, enhancing content access directly from the reader.
Supports plugins for adding functionality and over-the-air updates for easy maintenance, allowing users to extend features as needed.
Cons
Installation requires device-specific steps documented in separate wiki pages for Kindle, Kobo, etc., which can be daunting and error-prone for non-technical users.
No official support for iOS or Windows, restricting its use to Android, Linux, and specific e-ink devices, unlike more universal reading apps.
Relies on volunteers for translations, bug fixes, and documentation via Weblate and forums, which might lead to slower updates and inconsistent support.
Lacks native cloud synchronization for reading progress and libraries, requiring manual setup with external tools like calibre for cross-device continuity.
Frequently Asked Questions
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