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Karakeep vs Briefkasten: catalog facts
Karakeep	Briefkasten
Free The open-source software is available without a license fee. Hosting, hardware and…	Free Free and open source under the MIT licence.
Self-hosted, Web, Browser extension	Web, Self-hosted
Includes search and optional AI-assisted organization.	Self-hostable with Docker files included Also offered as a hosted instance
AI features require a separately configured model provider.	Setup needs a database and an OAuth provider configured No tagged releases
Self-hosted, Browser extension	Self-hosted, Hosted service
Open source	Open source
License: AGPL-3.0	License: MIT
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 2, 2026

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