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Orion Viewer vs ReadBear: catalog facts
Orion Viewer	ReadBear
Free Free and open source under the GPL.	Free Free and open source under the MIT licence.
Android	Android
Opens DjVu as well as PDF, XPS, CBZ and TIFF Configurable tap zones and key bindings for page turning	Reads PDF and CBZ comic files in one app Many reading options: layout, theme, spacing, language
Viewer only, with no PDF editing Interface is functional rather than polished	EPUB support is described as unfinished Small, young project with one main developer
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0-or-later	License: MIT
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 October 2, 2026

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