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Viber vs Threema: catalog facts
Viber	Threema
Free Free to download and use for messages and calls.	Paid A one-time purchase is required. Business plans are separate.
Android	Windows, macOS, Linux, Android, iOS, Web
Voice and video calls plus group chats Chats sync between mobile and desktop	No phone number or email required; the ID is random Apps are open source and the company is based in Switzerland
Proprietary and centrally run Communities and stickers add clutter for people who only want chat	A one-time purchase is required for each platform Smaller user base than the mainstream encrypted messengers
Downloadable app	Downloadable app
Closed source	Open source
License not stated	License: AGPL-3.0
Not stated if an account is needed	Not stated if an account is needed
Needs internet	Not stated if it works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 22, 2026

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