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OkularSumatra PDF
Free

Free and open source under the GPL.

 Free

Completely free and open source with no ads, bundled software or subscription. No account…

Windows, macOS, Linux Windows, Command line
  • One viewer for a very wide range of document and comic formats
  • Annotations are stored separately, so the original file is untouched
  • Opens PDF, EPUB, MOBI, FictionBook, CBZ/CBR/CBT/CB7, DjVu, XPS, CHM, SVG and many image formats including HEIC and AVIF
  • Lightweight and fast; the portable single .exe build writes nothing to the registry
  • Pulls in KDE libraries on non-KDE desktops
  • It is a viewer and annotator, not a PDF editor
  • Windows only (Windows 7 through 11; XP and Vista need version 3.1.2); no macOS or Linux version
  • Only unencrypted EPUB and MOBI/AZW ebooks open; DRM-protected files are not supported
Downloadable app Downloadable app
Open source Open source
License: GPL-2.0 License: GPL-3.0
Not stated if an account is needed Not stated if an account is needed
Not stated if it works offline Not stated if it works offline

Checked September 22, 2026

Checked September 20, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.