Huddle Inc., which is one of a growing line of well-capitalized companies in the suddenly hot enterprise collaboration market, said the U.S. version of its cloud collaboration service is the first to be granted Federal Risk and Authorization Management Program (FedRAMP) Authority to Operate (ATO) by the United States Agency for International Development (USAID). That’s Washington-speak for saying that the company now meets all necessary security requirements to sell into U.S. government agencies.

The approval enables Huddle to extend an already strong market presence it has built in the United Kingdom, where it claims to have 80% of central U.K. government departments as customers. Huddle said it has also sold licenses into the National Aeronautics and Space Administration, the Office of the Secretary of Defense and the National Institutes for Health.

“This should give us a first-mover advantage for secure collaboration,” said CEO Morten Brøgger. “We expect we will quickly get a big increase in dialog with a lot of U.S. government customers.”

Huddle’s collaboration service is built around a shared document metaphor, in which multiple users can edit, share tasks and assign workflows, with all interactions logged for review and compliance purposes. It’s fully integrated with Microsoft SharePoint and uses the native Microsoft document store.

While Brøgger said SharePoint is his company’s main competitor, he added that the two services coexist in 90% of installations. “Collaboration through Sharepoint across firewalls is difficult, costly and time-consuming,” he said. “Huddle gives you a modern, mobile-oriented platform. We’re the frosting that fills the gap in the SharePoint cake.”

Investors are eager to get a taste of that confection. They’ve poured more than $89 million into Huddle in seven rounds. The company claims to have more than 100,000 customers paying the minimum $20-per-user license fee.

Collaboration software has been around for decades, but it has mostly under-delivered on heady expectations. However, the success of document-sharing services like Dropbox, Inc. and Box, Inc., as well as the general froth in the venture capital market,  has rekindled excitement.

Slack Technologies, Inc., maker of the enterprise messaging platform Slack, has been widely reported to be in talks to raise capital at a valuation of between $2 billion and $2.6 billion. That’s double the valuation it received in a $120 million round less than six months ago.