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Flow vs Koodo Reader: catalog facts
Flow	Koodo Reader
Free Free and open source; self-hosting costs only your own server.	Free Free and open source under the AGPL-3.0.
Web, Self-hosted	Windows, macOS, Linux, Android, iOS, Web
Reads EPUB files directly in the browser Docker and docker-compose files for self-hosting	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 EPUB rather than a wide range of formats Self-hosting requires running a server	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
Not stated if it 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.