Slack, the best 4 in 1 solution

Slack is the central communication tool for our organization. When I started, we were only really using Slack for instant messaging. That has grown over the years to the point where we use Slack for internal calls, messaging, company wide and private communication channels, online meetings, and inter-office calling. I really like the evolution of the solution and it has replaced multiple tools that we'd otherwise use in our organization (like email, gotomeeting) into one single solution. I really like the mobile app and the experience between devices is seamless. My only nit-pick is that sometimes searching within the app can be a little wonky. Finally, the api for the system is nice and allows for nice integrations with our internal project management tool. Their app store is also comprehensive and the salesforce integration is useful.