# Orion Viewer (open-source reading app)

> 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.

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

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/max-kammerer/orion-viewer |
| Platforms | Android |
| Built with | Kotlin |
| GitHub stars | 308 |
| License | GPL-3.0-or-later (open source) |
| F-Droid | https://f-droid.org/packages/universe.constellation.orion.viewer/ (package universe.constellation.orion.viewer) |
| F-Droid anti-features | none flagged |
| Google Play | https://play.google.com/store/apps/details?id=universe.constellation.orion.viewer |
| App Store | not linked |
| Website | https://github.com/max-kammerer/orion-viewer |
| Official | no |
| Category | E-book, PDF & RSS readers |
| Latest release | 0.97.3 (Oct 2, 2026) |
| Last commit | Oct 3, 2026 |

F-Droid builds its apps from source and flags anti-features: https://f-droid.org/en/docs/Anti-Features/

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