Slack launches an app store and an $80 million fund to invest in new integrations

Slack is wrapping up a breakout year with a set of announcements designed to press its advantage as a next-generation productivity app. The team-communication app, which now has 2 million daily users and 570,000 paying customers, has established an $80 million fund to invest in companies who build Slack apps and other products that rely on integration with the company. (The fund is backed by Slack along with venture capital firms Accel, Andreessen Horowitz, Index Ventures, Kleiner Perkins Caufield Byers, Spark Growth, and Social + Capital.) Slack has also set up an “app directory” where administrators can browse the 150 integrations that are now available — Twitter, Dropbox, Trello, and Google Drive among them — and install them on their team’s Slack instance.

There’s news for developers, too: the team released a suite of new APIs designed to make it easier to build new apps on top of Slack. The most intriguing of these is BotKit, an open-source framework for building services that users access through conversational interfaces. It builds on Slackbot, which sends messages to new users to help orient them to Slack. The popularity of Slackbot among users has led developers to create bots that provide separate services within Slack. Howdy, to name one, is a startup whose bot runs “virtual meetings” that check in with employees and report back their findings to managers. Another, called Birdly, automates expense reporting.

The expanding platform and fund to support it have at least two big benefits for Slack. The first is that the company will be able to see in real time which new applications built on top of Slack are most popular, likely shaping its own product roadmap through acquisitions and feature additions. The second is that adding useful new apps is a proven strategy for attracting and retaining new customers.

Slack built all of its initial integrations itself, starting with Google Docs, Github, and a bug tracker, among others. The team’s insight then, which helps explain its meteoric rise, is that those integrations fueled all-day usage of Slack. “The more information you pushed into the messaging system, the more people paid attention to it,” says Stewart Butterfield, Slack’s founder and CEO. “It was a virtuous circle. We didn’t realize how strategic it would be as a business deal until after Slack had launched. And then suddenly it was just very obvious — the more apps we get people to install, the more likely they are to keep using Slack.”