Slack – Slack Technologies, Inc.

• Real time messaging and file sharing for one-to-one and group conversations
• Powerful search and archiving, so you can find information easily
• Hundreds of integrations with apps and services including Dropbox, Asana, Google Drive, Twitter, Zendesk and more
• Instantly syncs across all devices
• Configurable notifications for desktop, mobile, and email
• Scientifically proven (or at least rumored) to make your working life simpler, more pleasant, and more productive

Slack is available for free for as long as you want, with upgradeable plans for increased membership, extended message history, unlimited integrations, file storage and customizable data retention policies.

"There are two types of people in the world: those who have never heard of Slack, and those who can’t imagine life without it." — The Guardian

"Can't praise it enough. Slack transformed the way we work together at The New York Times.” – Michael Villasenor, Creative Director, The New York Times