• by Gavin O'Malley  @mp_gavin, May 10, 2016

Like Facebook and other platforms, Slack is trying to position itself as a digital gatekeeper for third-party app developers.

Unveiled on Tuesday, a new Sign in with Slack service is a way for customers to simply sign-up for apps using their Slack identity.

But, because Slack is a productivity messaging service, the new feature is more than a mere login. Rather, it promises to keep teams connected across various work-related apps.

Additionally, when users signs up for apps using Sign in with Slack, they will be automatically connected to designated teammates within the app.

Slack has recently established itself as a company to watch in the white-hot mobile messaging space. Since the spring, the start-up has more than doubled its daily active users to 2 million and nearly tripled its subscriber base to about 570,000.

Standing apart from rival messaging services -- namely Facebook -- Slack has convinced subscribers to fork over monthly fees for premium features.

To quickly scale it business, Slack recently raised $200 million at a valuation of $3.8 billion. New investors included Thrive Capital, Comcast Ventures and GGV. The startup had previously raised $340 million from Index Ventures, Andreessen Horowitz and Accel Partners, among others.

Like other platforms, Slack has aggressively courted the developer community. Late last year, for example, it started an $80 million venture fund to support the creation of apps and add-ons that complement its business-focused group-messaging service.

The fund has already invested in Awesome -- a tool that organizes Slack activity -- along with a productivity software maker and a toolkit for building chat bots.

Slack is financing more than half of the total fund, while the remainder should come from its existing backers, including Accel Partners and Andreessen Horowitz.

To further encourage a complementary ecosystem, Slack also developed an app directory to show users how they can integrate apps into their chat rooms. At last count, there were about 150 such applications.

Complicating Slack’s expansion plans, Facebook recently rolled out “Work Chat” -- a new messaging app designed specifically for business teams. Between its WhatsApp unit and Facebook Messenger, Facebook already dominates the mobile messaging space.

But Slack seems determined to change that. Vying for a bigger piece of the group-messaging marketplace, it recently began rolling out a conference-calling feature named Calls.