Dropbox

Dropbox has quietly acquired a workplace chat service startup called Zulip, according to TechCrunch.

While the two companies are keeping mum on the buyout, an email that Zulip sent its customers was published on Pastebin Monday. In the email, the company confirmed the acquisition.

"We have some news for you, but you gotta keep it secret. Can you do that? Alright, sweet," the email said. "Here's the deal: Dropbox is acquiring Zulip. We're incredibly excited about working with an awesome group of people on a problem with huge scale, at a company that's as passionate as we are about helping people work together efficiently."

Zulip was mostly founded by ex-Oracle employees like Jeff Arnold, Waseem Daher, Jessica McKellar, Tim Abbott, and others, according to TechCrunch. The service is still in private beta but has been working to build itself out as a workplace messaging service, like Yammer or Convo. Users can chat, share files, and search previous posts and messages.

Dropbox has snapped up quite a few startups over the past couple of years. In December 2012, it bought music streaming service Audiogalaxy and cloud-based photo organizer Snapjoy. In 2013, Dropbox acquired mobile-app maker Endorse and a company called Sold that aimed to make it easier for people to sell stuff online.

The terms of the Zulip acquisition are unclear, although in its email the company did say that the service would continue as "business as usual" for its customers.

When contacted by CNET, a Dropbox spokesperson said, "We have nothing further to share at this time."