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ッツ Ebook Reader vs Koodo Reader: catalog facts
ッツ Ebook Reader	Koodo Reader
Free Free to use, with the source code published on GitHub.	Free Free and open source under the AGPL-3.0.
Web, Self-hosted	Windows, macOS, Linux, Android, iOS, Web
Works with Yomitan and similar dictionary extensions Runs in the browser with nothing to install	Over fifteen formats including EPUB, PDF, MOBI, AZW3, comic archives and DOCX Syncs through storage you already control rather than a vendor cloud
Focused on Japanese reading rather than general ebook management Dictionary lookups depend on a separately installed browser extension	It reads DRM-free files only; books bought from a store with DRM will not open Sync depends on whatever storage you configure, so the setup is on you
Web application, Self-hosted	Downloadable app, Web application
Open source	Open source
License not stated	License: AGPL-3.0
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 September 20, 2026

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