Chatra — Live Chat & Chatbot

Setup in minutes, including a perfectly integrated iphone app. I was using Olark before but they had a really complex setup for mobile through a third-party app. Chatra is unified perfectly between laptop and phone and doesn't get tripped up if I try to use both in one conversation.
The only drawback was that customizing exact colours required some API code to be added to the site.
I highly recommend this app. In fact, I can't think of a reason why anyone wouldn't use this.