When comparing Jitsi vs Threema, the Slant community recommends Jitsi for most people. In the question“What are the best Skype alternatives?” Jitsi is ranked 2nd while Threema is ranked 10th. The most important reason people chose Jitsi is:
Project available on github for anyone to contribute to or use.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Open-source
Project available on github for anyone to contribute to or use.
Pro Cross platform
Mac, Windows & Linux availability.
Pro Video calls
Pro OMEMO encryption without plugin
Secure Jabber Texting, better than legacy sms texting.
Pro Supports SIP accounts
well implemented SIP SIMPLE (texting), SIP presence, XCAP.
Pro Supports XEP-0016 and privacy Lists
Jabber Texting apps without Privacy Lists are WOEFULLY deficient.
Pro Encryption out of the box
Encryption for chat, desktop sharing, and web confrencing available.
Pro Registration without phone number
Registration is handled by random generated IDs. No phone number needed.
Pro Encrypted communication
Provides complete end-to-end encryption.
Pro Company behind Threema is based in Switzerland
Pro Servers in Switzerland
Privacy laws protect the data Threema has.
Pro Supports encrypted group chats
Pro Provides a web client
You can control and message with friends via Threema Web, the official web client for Threema.
Pro Ability to send pics and videos
Threema supports sending media messages such as video, pics and even voice messages.
Pro Group chat polls
Pro Allows verification of contacts identity via QR Code
Cons
Con Crashes on MacOS Monterey
Con Abandoned Android development
They switched focus to Jitsi Meet client for Android.
Con Uses Java
Not a native app, takes awhile to load.
Con Gui not as slick or streamlined as competitors
Con Not free
Unlike many other options Threema is not free as it costs $1.99 for the app.
Con Single device only
You cannot use multiple devices to send messages. However, it does have message mirroring on a web client.
Con No cloud sync
E2E encryption means no cloud syncing of messages.