Workplace chat service Slack will now let users interact with third-party services without ever having to leave the app. The new feature, called message buttons, lets companies create interactive Slack apps for performing tasks from within the chat window, like approving expense reports or booking a trip. For example, companies that rely on the project-management software Trello can now create new project cards, add members to those cards, and set due dates for the project all by clicking buttons in a Slack channel.

Slack has 12 launch partners for the initiative, including Trello, travel site Kayak, recruiting service Greenhouse, and expense report app Abacus. To start, Slack will let developers add up to five buttons per attachment, but the company plans to expand the feature to let third-party services perform even more complex tasks. And so long as Slack doesn't set out to replace the services it supports, it will continue working in tandem with app makers. "When we ask developers what success means to them, it’s about usage, engagement, and keeping customers," says Buster Benson, a senior product manager at Slack. "That’s entirely in line with our own goals."

Slack is fast becoming the operating system of the workplace

This feature may only sound important to tech-minded businesses, but it does mean Slack is fast becoming what you could consider the operating system of the workplace. By letting third-party services build on top of its application, Slack as a platform becomes increasingly more versatile. As a result, users won't leave Slack quite as often to perform tasks in other apps or on the web. The goal, from Slack's perspective, is to make nearly every workplace action accomplishable using its chat window. Adding something as simple as buttons to a standard message is a powerful step in realizing that vision, when you consider those buttons are tied to actions that would normally require five or six extraneous steps to perform.

Slack, with about 3 million daily users and nearly one-third of them paying customers, is one of the fastest-growing business apps in the tech industry. But to keep getting bigger and attracting ever-larger customers, the company has to continue expanding beyond a chat service for communicating with coworkers into a full-blown platform for completing all sorts of different tasks. Slack will only replace traditional enterprise software if its more efficient than everything else on the market.

The company has more than 500 apps available since the launch of its app store in December. A majority of those can be configured to work specifically with how an organization uses and relies on Slack to get work done. Making those apps interactive in new ways only makes the service, an addictive app in its own right, even harder to put down. "We don’t have an opinion about keeping people in Slack, but it’s really about bringing all the tools together in a command center for teams," says Benson.