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Readwise Reader vs Cauldron: catalog facts
Readwise Reader	Cauldron
Paid Paid subscription.	Free Free and open source under the Apache-2.0 licence; requires an Instapaper account.
Windows, macOS, Android, iOS, Web, Browser extension	Linux
Handles many content types in one inbox, not just web articles Deep highlighting and search tools for power readers	Native GTK interface for GNOME Reads saved Instapaper articles outside the browser
Paid subscription required Most valuable when paired with the separate Readwise highlights product	Only works with Instapaper Linux only
Downloadable app, Web application, Browser extension	Downloadable app
Closed source	Open source
License not stated	License: Apache-2.0
Not stated if an account is needed	Account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked October 1, 2026

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