KOReader
KOReader: A free, open-source reader with broad format support and deep Calibre integration. Ranked #6 of 27 in Ebook Reader Software by our editors (8.6/10); pricing: Free plan; best for open-source readers using ereaders and Calibre.
At a glance
- Editor score8.6 / 10
- PricingFree plan
- Best forOpen-source readers using ereaders and Calibre
- Free planYes
- Paid fromFree
- Annotation toolsYes
- Facts checked23 Sep 2026
Where it wins
- Opens ebook and fixed-page formats including EPUB, PDF, DjVu, and MOBI
- Calibre tools cover metadata search, wireless transfers, and OPDS browsing
- Custom typography, bookmarks, highlights, and PDF controls support varied reading
Where it doesn't
- Progress Sync works between KOReader devices, and each needs its own document copy
- The wiki says note-taking is not supported
- macOS is listed via emulator rather than as a native platform
Our verdict on KOReader
KOReader is a free, open-source document reader aimed primarily at E Ink devices, with versions for supported ereaders, Android, and desktop Linux. It suits readers who want control over typography and a broad choice of ebook and fixed-page formats, including EPUB, PDF, DjVu, XPS, MOBI, and ZIP. Text search, bookmarks, highlights, dictionary lookup, and Wikipedia lookup cover common reading tasks. It is a particularly relevant option for people who already organize a library with Calibre or prefer open-source software.
Calibre integration is a central strength rather than a peripheral connection: KOReader supports metadata search, wireless ebook transfers, and OPDS library browsing. The listed ecosystem also includes Wallabag, Wikipedia, and Google Translate, while plugins extend the reader and a Progress Sync plugin synchronizes reading position between KOReader devices. That sync has a practical constraint: each device needs its own copy of the document. Platform coverage is strongest for ereaders, Android, and desktop Linux; macOS is listed via emulator. Readers should check that their particular device is supported before choosing it.
For document handling, KOReader offers customizable margins, line spacing, fonts, and styles, plus PDF zoom, cropping, contrast adjustment, and reflow. These controls make it useful for people who read both flowing ebooks and fixed-page files. There is no paid tier to weigh against these features: KOReader is open source, and the project describes volunteer development with donation support. Community and documentation are its support channels. Choose it if broad format support, ereader use, and Calibre workflows matter more than a polished commercial support model. It is less suitable for readers who need built-in note-taking; bookmarks and highlights are supported, but the wiki says note-taking is not.
Your product? Our editors can test KOReader in depth and publish a review, labelled as paid · from $149/mo →
KOReader pricing
KOReader fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Supported platforms | Kindle, Kobo, PocketBook, Android, desktop Linux; macOS emulator |
| Supported formats | EPUB, PDF, DjVu, XPS, CBT, CBZ, FB2, PDB, TXT, HTML, RTF, CHM, DOC, MOBI, ZIP |
| Annotation tools | Yes |
| Reading sync | Yes |
| Offline reading | Not verified |
| Library storage | Not verified |
| Deployment | Self-hosted, Desktop, Mobile |
| Platforms | Linux, macOS, Android |
| Support | Community, Docs |
| Built for | Solo (editorial estimate) |
| Integrations | 4 integrations: calibre, Wallabag, Wikipedia, Google Translate |
| Pricing | Free plan |
| Website | koreader.rocks |
| Facts checked | 23 Sep 2026 |
KOReader integrations
KOReader lists 4 integrations on its own site.
- calibre
- Wallabag
- Wikipedia
- Google Translate
Alternatives to KOReader
- ReadestA cross-platform ebook reader for broad format support and detailed annotations.9.4
- BookFusionA flexible cloud library for mixed-format readers who want offline access and sync.9.2
- PocketBook ReaderA format-rich free reader for mobile users who need Adobe DRM and reading-position sync.9.0
See all KOReader alternatives →
KOReader vs the competition
- KOReader vs Readest
- KOReader vs BookFusion
- KOReader vs PocketBook Reader
- KOReader vs Thorium Reader
- KOReader vs Moon+ Reader
- KOReader vs eBoox
Compare KOReader with any tool side by side →
Also Ranked In
KOReader is ranked in 2 of our directories.
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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