Viber shares a founder with one of those Israeli shitware companies from Download Valley and has ties to several others https://en.wikipedia.org/wiki/...

Also, they have questionable security and/or sold people contacts in the past http://haydenjames.io/i-refuse...

On November 4, 2014, Viber scored 1 out of 7 points on the Electronic Frontier Foundation's "Secure Messaging Scorecard". Viber received a point for encryption during transit but lost points because communications were not encrypted with keys that the provider didn't have access to (i.e. the communications were not end-to-end encrypted), users could not verify contacts' identities, past messages were not secure if the encryption keys were stolen (i.e. the service did not provide forward secrecy), the code was not open to independent review (i.e. the code was not open-source), the security design was not properly documented, and there had not been a recent independent security audit.

On top of Opera being very fast, the sync feature is also nice if you have a lot of bookmarks dating back years. The new opera beta for the desktop has a built in 'sync' to sync the bookmarks with my.opera.com (same thing as Foxmarks plugin on firefox). All you need to do to get your bookmarks on your phone is import your firefox bookmarks into desktop opera, and sync mini opera for the win.