Slack is an application that helps teams communicate and work together by combining messaging, file sharing, and app integrations in one place. It makes it easy for teams to stay connected and work efficiently, whether they are in the office or working remotely.

Instantly reach the people in your life—for free. Messenger is just like texting, but you don't have to pay for every message (it works with your data plan).

WhatsApp Messenger is a FREE messaging app available for iPhone, Android, and other smartphones. WhatsApp uses your phone's Internet connection (4G/3G/2G/EDGE or Wi-Fi, as available) to let you message and call friends and family. Switch from SMS to WhatsApp to send and receive messages, calls, photos, videos, documents, and Voice Messages.