Viber made most of the features like messaging, voice call, group call available for free to all the users. There are also optional paid features offered by Viber as listed below.
1. Viber users can send free or paid stickers in the chat.
2. For a low rate, user can make calls to any phone number in the world from the Viber app using Viber out
3. There are few paid options in Viber Games.
4. In addition, Viber displays ads within the Viber app, which are clearly marked as sponsored