Orion Viewer
Orion Viewer is a free, open-source reading app for Android. Orion Viewer is pdf, djvu, xps, tiff and comic books (cbr, cbz, cbt) file viewer. It has 308 GitHub stars and is released under the GPL-3.0-or-later license, and you can install it from F-Droid and Google Play.
About Orion Viewer
Orion Viewer is pdf, djvu, xps, cbz and tiff file viewer for Android devices based on mupdf and DjVuLibre libraries. Outline navigation Bookmarks support Page navigation by screen taps + Tap Zones + Key binding Text selection Single word selection by double tap with translation in external dictionary Custom zoom Custom manual and auto border crop Portrait/landscape orientation Support different navigation patterns inside page (left to right, right to left) External Dictionaries support Built-in file manager with recently opened file view
Privacy and F-Droid
F-Droid builds Orion Viewer from its published source code and flags anti-features such as ads, tracking or reliance on non-free services.
No anti-features flagged on the latest F-Droid build.
Screenshots
Screenshots from the app's F-Droid listing.
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What is Orion Viewer?
Orion Viewer is a free, open-source reading app for Android. Orion Viewer is pdf, djvu, xps, tiff and comic books (cbr, cbz, cbt) file viewer. It has 308 GitHub stars and is released under the GPL-3.0-or-later license, and you can install it from F-Droid and Google Play.
Is Orion Viewer free and open source?
Yes. Orion Viewer's source code is public on GitHub under the GPL-3.0-or-later license, which is OSI-approved or FSF-free. F-Droid, which builds it from source, flags no anti-features such as ads or tracking on its latest build.
How do I install Orion Viewer?
You can install Orion Viewer from F-Droid (package universe.constellation.orion.viewer) and from Google Play; the links are on this page. Its GitHub repository also publishes releases (latest: 0.97.3).
Is Orion Viewer still maintained?
The repository's most recent commit was on Oct 3, 2026. Its F-Droid listing was last updated on Oct 3, 2026. appsgit only lists apps whose repository had a commit in the last six months.