LinkedIn today announced that it now has 300 million registered users on its platform with roughly two-thirds of them based outside the US.

Considering that LinkedIn’s goal is to create economic opportunity for all 3.3 billion global workforce members, the company has hit 9 percent of its goal with just 3 billion left to go.

I asked LinkedIn how many of its registered users count as monthly active users, but the company declined to provide a number. It does, however provide visitor numbers during its quarterly earnings reports. For the fourth quarter of 2013, LinkedIn had 139 million monthly unique visitors and 48 million Slideshare visitors.

During the same period, 41 percent of LinkedIn’s traffic came from mobile devices. The company expects that to tip over to a majority sometime this year. LinkedIn says mobile traffic brings in 15 million profile views, 1.45 million job views and 44,000 job applications every day across 200 countries.

As LinkedIn approaches its “mobile moment,” the company is in the midst of a massive training effort to equip all of its engineers for mobile development. Kiran Prasad, LinkedIn’s Senior Director of Engineering – Mobile, explained the three parts of LinkedIn’s Mobilize initiative.

First, the company has moved to a multi-app strategy that views its collective mobile offerings as a suite of apps for its users. New products such as the new Slideshare Android app offer functionality for specific use cases. The approach is similar to Facebook, which has started to break out features, such as messaging, into standalone applications.

In designing its apps, LinkedIn uses a “five-second rule.” If users can’t understand what an app does in the first five seconds after opening it, then it’s too complex.

Second, LinkedIn is conducting company-wide training for iOS, Android, and HTML and Javascript mobile Web development. A quarter of its engineers have gone through the courses, while non-engineers can also receive training in mobile UI and product management.

LinkedIn’s third piece for Mobilize is focused on the platform. Prasad noted that the company has spent the past couple years building up discrete databases, dubbed Super Blocks, for managing major objects such as profiles, companies and job listings. Then, it constructed a pipe system, called Rest.li, for connecting its mobile apps with these databases. LinkedIn has also invested resources in internal mobile SDKs to get its applications to collaborate.

“It has literally taken us 2 1/2 years of investment around making the Super Block and Rest.li happen. Almost any company that has to go through this shift of Web to mobile has to effectively re-architect their core infrastructure in a significant way,” Prasad said.

Despite LinkedIn’s aggressive focus on mobile as of late, Prasad emphasized that LinkedIn isn’t treating the future as a “mobile-only world.” Instead of taking a mobile-first approach like many companies, LinkedIn is working on simultaneously shipping across mobile and desktop.

Moving forward, LinkedIn plans to ramp up its multi-app strategy with several more releases this year and even more in 2015. The company is also prioritizing phone number integrations and push-based interactions for its apps to meet the needs of its growing mobile audience. Prasad also indicated plans to take better advantage of LinkedIn’s powerful data with “platform-integrated instant insights” with the kind of intelligence that Google Now and Siri are known for.

LinkedIn isn’t the most buzz-worthy of the major social networks, but it has become an essential layer of the modern workforce. 300 million registered users is a solid milestone, and, with its latest mobile push, LinkedIn’s just getting started.

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