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Adobe Acrobat Reader vs Orion Viewer: catalog facts
Adobe Acrobat Reader	Orion Viewer
Freemium Free to use; editing and conversion require a paid Adobe Acrobat subscription.	Free Free and open source under the GPL.
Windows, macOS, Android, iOS	Android
Faithful rendering of complex PDFs and forms Form filling, signing and annotation included free	Opens DjVu as well as PDF, XPS, CBZ and TIFF Configurable tap zones and key bindings for page turning
Frequent prompts to upgrade to paid Acrobat Large install compared with lightweight readers	Viewer only, with no PDF editing Interface is functional rather than polished
Downloadable app	Downloadable app
Closed source	Open source
License: Proprietary	License: GPL-3.0-or-later
Not stated if an account is needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked October 2, 2026

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