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KOReader vs ReadEra: catalog facts
KOReader	ReadEra
Free Free and open source under the AGPL 3.0.	Free Free to download and use without ads, according to the developer.
Linux, Android	Android, iOS
Runs on Kindle, Kobo, PocketBook, Cervantes and reMarkable hardware Opens PDF, DjVu, CBZ, EPUB, FB2, Mobi, DOC, RTF, HTML, CHM and TXT	Opens EPUB, MOBI, PDF, DjVu, Word, FB2 and comic files Reads books directly from ZIP and RAR archives
Installing on a locked e-reader means jailbreaking it first, at your own risk The settings menus are deep and not self-explanatory	Closed source Mobile only, with no desktop version
Downloadable app	Downloadable app
Open source	Closed source
License: AGPL-3.0	License not stated
No account needed	No account needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked September 21, 2026	Official website Full listing and sources Checked September 23, 2026

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