SumatraPDF vs KOReader

SumatraPDF9.0Visit KOReader8.8Visit

Higher score SumatraPDF #4 in File Reader Software 9.0/10 Free plan Free plan✓ 1 of 4 features Visit Sumatra PDF

vs

KOReader #5 in File Reader Software 8.8/10 Free plan Free plan✓ 1 of 4 features Visit KOReader

• SumatraPDF fits best

  Windows users who want a capable free reader

• KOReader fits best

  Open-source readers across ebook and document formats

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Side by side

Feature	SumatraPDF 9.0/10 Visit ↗	KOReader 8.8/10 Visit ↗
At a glance
Editor score	9.0	8.8
Ranking	#4 in File Reader Software	#5 in File Reader Software
Best for	Windows users who want a capable free reader	Open-source readers across ebook and document formats
Pricing model	Free	Free
Starting price	Free plan	Free plan
Free plan	✓	✓
Free trial	—	—
Deployment	Desktop	Self-hosted, Desktop, Mobile
Platforms	Windows	Linux, macOS, Android
Support	Docs, Community	Community, Docs
Built for	Solo, Small business, Mid-market, Enterprise	Solo
Features SumatraPDF 1/4 · KOReader 1/4
Annotations	✓	✓
Text search	Not checked yet	Not checked yet
Accessibility support	Not checked yet	Not checked yet
Cloud sync	Not checked yet	Not checked yet
Specs
Supported formats	Not checked yet	Not checked yet
Platforms	Not checked yet	Kindle, Kobo, PocketBook, Android, desktop Linux; macOS emulator
Our review
Pros	Opens PDFs, ebooks, comics, DjVu, XPS, CHM and images Supports PDF annotations, form filling, search and read-aloud Portable build runs without installation or registry writes	Opens ebook and document formats including EPUB, PDF, DjVu, and MOBI Customizable typography, search, bookmarks, and highlights Calibre integration and optional cross-device reading-position sync
Cons	Available for Windows only OCR support is not included Some editing and accessibility features are documented for pre-release 3.7	Platform coverage varies across e-readers, Android, Linux, and macOS emulator Progress Sync requires a separate copy of the document on each device Bookmarks and highlights are supported, but note-taking is not
Our verdict	Sumatra PDF is a free, open-source desktop reader for Windows, suited to people who want one lightweight app for PDFs and a range of other reading formats. It opens EPUB, MOBI, comic-book files, DjVu, XPS, CHM and images as well as PDFs.… Read the review →	KOReader is a free, open-source document reader aimed primarily at E Ink devices, with versions also available for Android and desktop Linux. It suits solo readers who want control over typography and access to ebook and fixed-page… Read the review →

Strengths and trade-offs

• SumatraPDF — where it wins

  • Opens PDFs, ebooks, comics, DjVu, XPS, CHM and images
  • Supports PDF annotations, form filling, search and read-aloud
  • Portable build runs without installation or registry writes

  Where it doesn't

  • Available for Windows only
  • OCR support is not included
  • Some editing and accessibility features are documented for pre-release 3.7

• KOReader — where it wins

  • Opens ebook and document formats including EPUB, PDF, DjVu, and MOBI
  • Customizable typography, search, bookmarks, and highlights
  • Calibre integration and optional cross-device reading-position sync

  Where it doesn't

  • Platform coverage varies across e-readers, Android, Linux, and macOS emulator
  • Progress Sync requires a separate copy of the document on each device
  • Bookmarks and highlights are supported, but note-taking is not

• SumatraPDF9.0/10 · Free plan

  A format-flexible Windows reader with annotations, forms and portable operation at no cost.

  Visit Sumatra PDFFull verdict →
• KOReader8.8/10 · Free plan

  A format-flexible reader with annotations, PDF controls, and optional reading-position sync.

  Visit KOReaderFull verdict →