Probably slack and ryver and facebook for work - there's a lot of companies out there. And other companies are throwing money into it too. Cisco just put out

Probably slack and ryver and facebook for work - there's a lot of companies out there. And other companies are throwing money into it too. Cisco just put out a $150mil fund to fund similar things for their chat & video platform as well: https://developer.ciscospark.com/fund/ https://developer.ciscospark.com/fund/ Disclaimer: I do work for Cisco