Most Innovative Companies


Slack is a cloud-based team communication tool developed in 2013 by Canadian entrepreneur and now-CEO Stewart Butterfield. 

In 2018, Slack introduced Actions, which turns talk into tasks. Users have the option of taking action on a conversation, connected to apps installed on their workspace. Slack also upgraded its search functionality, improving its predictive abilities as well as its speed. 

Slack was originally meant to be an internal communication tool at Butterfield's small company Tiny Speck, as his team developed the now-defunct online game Glitch. But by 2015, Slack had become a tech and media darling for its ease of use and fun in-app features. It works by offering communication over topic-based "channels" in the form of internet relay chat that allows collaborators to tag each other in conversations, "star" responses, and even share files in the thread of a chat. It also offers private groups and direct message formats, as well as joyful features like a GIF-generating hack that pulls content from another playful company, Giphy, into a chat using a simple keyword text command. Slack has succeeded where other collaboration platforms have failed by making company communication not just easy, but fun. Its elegantly designed chat rooms and intuitive interface allow for instant team communication, essentially eliminating the need for email chains.

In 2017, Slack moved closer to its dream of killing office email with the launch of Enterprise Grid, a version of its workplace-messaging platform that offers separate spaces for different teams, along with cross-company channels and a unified directory. Another new product, Shared Channels, connects teams from different organizations to collaborate. With more than 9 million weekly active users (2 million paid), Slack’s annual recurring revenue has reached $200 million. “Whole companies want to use Slack at a scale we never anticipated,” says Noah Weiss, head of search, learning, and intelligence. Slack’s growing popularity as the productivity tool of choice has attracted $790 million in venture capital funding, including a Series G round of $250 million in September 2017 led by SoftBank.

valuation: $3.8 billion
public or private: Private
revenue: $25-$30 million
staff: 800+
users: 5 million daily users worldwide
headquarters: San Francisco, CA
Competition: Facebook, Microsoft