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Ferdium vs Altus: catalog facts
Ferdium	Altus
Free Free and open source under Apache 2.0. Unlike Franz, the project states it does not…	Free Free and open source under GPL-3.0.
Windows, macOS, Linux	Windows
Hundreds of services supported, with workspaces to group them No paid account or usage restrictions, unlike the Franz it forked from	Multiple WhatsApp accounts in one app Custom themes for the WhatsApp interface
Each service is a web view, so memory use grows quickly with many services Service integrations break when a provider changes its web app	Unofficial client that depends on WhatsApp Web Electron app with higher memory use than a native client
Downloadable app	Downloadable app
Open source	Open source
License: Apache-2.0	License: GPL-3.0
No account needed	Account needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 21, 2026	Official website Full listing and sources Checked October 2, 2026

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