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Orion Viewer vs Xodo: catalog facts
Orion Viewer	Xodo
Free Free and open source under the GPL.	Freemium Reading and annotation are free. Editing and conversion quotas require a paid plan.
Android	Windows, Android, iOS, Web
Opens DjVu as well as PDF, XPS, CBZ and TIFF Configurable tap zones and key bindings for page turning	The same annotation and signing tools on web, desktop and mobile Works directly against Google Drive, Dropbox and OneDrive
Viewer only, with no PDF editing Interface is functional rather than polished	Conversion and advanced editing are limited without a paid plan Closed source, and online tools process files on their servers
Downloadable app	Downloadable app, Web application
Open source	Closed source
License: GPL-3.0-or-later	License not stated
No account needed	Not stated if an account is needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked September 22, 2026

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