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

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