I am using Kaizala for last three months. I run a group with 500 odd people, and it is ready to go big. It is one of the best messaging apps both for private and team use. The number of users it can hold in a group is just remarkable. In every respect, it is better than the alternatives for me. Some of the top features include no storage limits, functional design, end-to-end encrypted chats, extra functionality like cards where one can add training module, polls, quiz, and many more.
Used this for sales team
This is a good product
Trying this is a pure waste of time.