That's nifty, but file-sharing is a core feature of many other collaborative platforms, and it's only the tip of the iceberg for Slack. The real power comes from adding in content from all the other systems that you use day-to-day.
Many of Slack's third-party integration options come straight from the wishlist of developers, including popular services like Github (code version control) and Zendesk (help desk ticket management). This sounds simple, but the possibilities are profound: When new code is pushed to a repository, everybody in a development team's channel can get an alert. There are tons of options, involving far too many services to list here, but I'll single out the irrepressible, terrible Yo.
It's not just for coders, either: Integrations with MailChimp and Twitter mean that a marketing team can get alerted in the context of a chat room when someone unsubscribes to a newsletter and then complains about it on social media. Type "/hangout" and a Google Hangouts video call starts with the people in that call, provided you've configured the integration. Response time goes down, and general situational awareness from having everything in a single hub goes up.
So yeah, Slack is cool. Where every other platform claws for user retention by trying to let you do more within the app itself (see Yammer and Salesforce), Slack meets users where they live, pulling both their social graph and data from the outside services they're already using into one über-feed that pushes the content together with the conversations around it, with a search bar for just about everything. No wonder people spend so much time in it.
A tech product for tech people
There are a couple of caveats here, though.
First off, Slack is probably not for everybody. While Slack boasts companies like Vox, Urban Outfitters, and Blue Bottle coffee as customers -- and, indeed, launched a website to highlight job openings at teams that use Slack — it's a most natural fit for developers. Those are the people within an organization whose job requires them to be in front of a computer, making a lot of changes to all-digital assets, all day every day.
A number of digital newsrooms, including stalwarts like The New York Times and The Guardian and new media darlings like BuzzFeed and Business Insider, have turned to Slack for their reporting teams. Same situation here — these people need to communicate quickly to create and modify digital assets.
For all the hype, Slack only really shines in the specific use-case of teams, likely distributed across geographies, who have to share and act on information from multiple sources really, really fast in order to produce something digital. It's probably not going to make as much sense for, say, a field sales force. Or the HR department. Or retail workers.
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