When comparing Viber vs Rocket.Chat, the Slant community recommends Rocket.Chat for most people. In the question“What is the best team chat software?” Rocket.Chat is ranked 7th while Viber is ranked 29th. The most important reason people chose Rocket.Chat is:
Rocket.Chat is available for free. It's licensed under the MIT license with source code available on [GitHub](https://github.com/RocketChat/Rocket.Chat).
Ranked in these QuestionsQuestion Ranking
Pro Desktop apps allow texting, calling and enables transferring calls between devices
Viber has native apps for both Windows and Mac that allow you to send and receive messages from your desktop. You can also use the desktop to make and receive calls. Synchronizes between all devices you are using Viber on. Allows transferring calls between devices.
Pro Supports voice calls
Viber has really well implemented voice tech. It has comparable quality to Skype and you can even tranfer calls from your phone to your desktop seamlessly.
Pro Completely free
Viber uses data connection and the app is free.
Pro Clean interface
The interface is simple, functional and intuitive.
Pro See who of your contacts is using Viber quickly
Viber is tied to your phone number so it can quickly see who else in your contacts list is using the application.
Pro Android Wear support
Viber includes Android Wear support on Android 4.3 or higher and Viber 5.3 or higher.
Pro Same protocol as used in Signal
Viber's protocol uses the same concepts of the "double ratchet" protocol used in Open Whisper Systems Signal application.
Pro Public chats
It's possible to be a fly on the wall on other group or one-to-one chats that have been opened up to the public. These public chats are often promotional chats with celebrities.
Pro Supports video calling over WiFi and data.
Can call friends using voice or video options.
Pro Combines cellular and data messaging
This has an advantage in that if you text someone who uses Viber it will be free, if not it will just revert to SMS. This means you can replace your standard messaging app with Viber as well.
Pro Keys only on device
Starting with Viber 6.0 the encryption keys are stored only on the clients themselves, not even Viber itself has access to them.
Pro No need to create an account or add contacts
One of the best things about Viber is how it handles setup and sending messages. Viber uses your existing number as your ID, so you don't need to create a separate Viber account.
Pro Supports 200 person group chat
Viber allows creating groups of up to 200 people on the Android version of Viber. It also has a cool "smart notifications" feature to prevent being overwhelmed with notifications if a lot of people are active in a chat group.
Pro Insight and well documented encryption
Viber has made a documentation available, explaining in great details their encryption system and giving good insight on how it works.
Pro Free and open source
Rocket.Chat is available for free. It's licensed under the MIT license with source code available on GitHub.
Pro Native apps for all major desktop and mobile platforms
Rocket.Chat has native apps for macOS, Windows, Linux, iOS and Android.
Pro Supports a wide variety of authentication methods
In addition to the usual email / username + password combination, Rocket.Chat supports authenticating via Facebook, Github, Gitlab, Google, Linkedin, Meteor and Twitter accounts.
Pro Understands markdown better than Slack does.
Links work properly, for instance, with square brackets followed by parentheses.
Pro Very active and helpful community
Pro Video conferencing support
Rocket.Chat supports video calls.
Con No web client
You cannot login from the web to send and receive messages.
Con The company evades U. S. tax
The company uses the common practice of tax haven addresses in order to avoid paying US taxes despite being registered in Delaware.
Con Constantly on
Need apps like Greenify to stop it from being constantly on and active, even if you don't use it.
Con Constant reminders of messages
If you don't check your messages (say your in a group chat and simply don't check all of them), it will flood your notifications.
Con Doesn't sync well
Sync awfully between Phone and PC clients.
Con Proprietary Software
Not Open Source.
Con Developer support is non-existent
Can't even create a clean Ubuntu VM with a working developer install. Unresolved dependencies; fails to build. Docs are terrible; actual devs don't respond to questions; error messages are near-opaque. DO NOT RECOMMEND.
Con Web client loses images
In chat rooms with images, before very long, images start to become empty boxes. Useless to pass around visual information
Con No theme customization
Con No chat audit for enterprise
Con Poor security implementations / protocols
Con iOS app is poorly made
The iOS application is not native, being just a browser container. This means that the UX is quite poor, slow, buttons unresponsive. At this moment they do not provide a decent experience.
Con Android app is poorly made
The Android application is just a badly wrapped web-view which does not perform well and has no form of offline caching whatsoever.
Con Privacy settings are absent
Privacy settings for the server are absent, for instance, you don't have the ability to disable registrations, there's no way to control access to the chat.
Con Features not available out of the box
Con No web browser support
Con Email required for registration
Con No way to block new registrations
Without the ability to disable registrations, there's no way to control access to the chat.