When Kiran Prasad joined LinkedIn in January of 2011, the company had an iPhone app – but just barely. The mobile design philosophy up until then had been to try and implement all of the features of LinkedIn on the web by throwing a different button for each feature into the mobile app. As a result, the app was covered in icons, many of which were rarely used. When Prasad arrived as director of engineering mobile, he prompted a reevaluation and redesign of just about every aspect of LinkedIn’s mobile technology. Prasad spoke with WebProNews about how he and his team were able to turn LinkedIn’s mobile apps into fast and easy-to-use platforms for professional networking, what the company’s mobile development philosophy is, and what’s next for LinkedIn’s mobile future.

In the past three months, LinkedIn has released both a redesigned iPad app and an app for Windows Phone. Both of those apps are streamlined and showcase only the most relevant information from LinkedIn, focusing on what users need and want. They demonstrate where LinkedIn’s mobile strategy is headed, that less is sometimes more, and that usability is key.

Prasad said that when he started at LinkedIn, his mobile engineering team consisted of four or five people. The team has grown to around 25 people in the past year and a half, but it is stil “by far the smallest team in the organization,” said Prasad. He emphasizes, though, that he doesn’t need a large team. He said that they pull from all the other teams at LinkedIn, taking all of the company’s products and placing them in a mobile context. “We’re standing on the shoulders of giants,” said Prasad

The goal of the mobile team is to try and build simple interfaces. To do that, Prasad said they go by the mantra “fast, easy, reliable” – in that order.

Prasad said the greatest focus is on speed because of how fast business is now done. It’s known that LinkedIn’s users are, for the most part, professionals who use the platform as a part of their career-building efforts. Also, Prasad said that users consume mobile content at a much faster rate than content on the web. For the site’s mobile applications to be of any use, they have to be able to keep up with the LinkedIn members using them.

The ease of use part of the mantra is more tricky, involving less technical prowess and more design sensibility. This is where Prasad’s past experience was brought to bear. Before he signed on at LinkedIn, Prasad worked as a software engineer at both Handspring and Palm. At Palm he spent over three years as senor director of core software, designing and implementing apps and services for WebOS and the Palm Pre. One design philosopy Prasad said he has brought with him is the idea of counting the number of taps a user must make to accomplish a specific task. More than three taps means the user is never going to find it.

Though reliability is the third and last focus of the mobile team’s mantra, Prasad emphasized that it is not ignored. He stated that a certain level of reliability is always necessary and maintained.

The redesign of mobile at LinkedIn began with the iPhone app. With all of the icons in the old app, it was easy for Prasad’s team to see what users were tapping on and what they were ignoring. These types of metrics, Prasad said, are used throughout LinkedIn, though he states that they are not the final say on how the company proceeds. “I wouldn’t say I’m metrics-driven, I’d say I’m metrics-informed,” said Prasad.

The team found that the feature most-loved by LinkedIn mobile users was the search function. Prasad surmised that users were using search to look up potential contacts or meeting-attendees on-the-fly. Because of this, the search function is now available on every screen of the iPhone app.

The team also found several features that were rarely, if ever, used. Color themes were thrown out, as well as business card transfer, a feature that sounds cool but was actually more trouble to use than simply handing over a normal business card.

In between these two extremes was what Prasad called the middle stuff, the features that were used, but not a huge focus for users. Prasad said he uses the metaphor of a house to help place the design of all those other features. Each room in the “house” represents a useful feature for a LinkedIn mobile user. The hallways connecting those rooms are the ways in which users navigate to their destination within the app. From the 12 rooms in the original iPhone app “house,” Prasad and his team were able to cut down the number of rooms to just four: the “stream”, “you,” “inbox,” and “groups & more.” The design of the new iPad app was even able to cut out “groups & more,” leaving just three “rooms.”

User interface design wasn’t the only area in which LinkedIn’s mobile apps were improved. In order to stick to their “fast, easy, reliable” mantra, the team had to re-engineer LinkedIn’s mobile tech stack from scratch.

The old stack was based in Ruby on Rails, meaning that, for each user, a server-side process was spawned and sent requests to the back-end. These requests were serial and limited in number, meaning a backlog of requests could mean delays for the end-user. “The biggest issue on mobile is latency,” said Prasad.

He and his team re-wrote the stack using javascript and Node.js. Now, one process is used server-side with a queue of requests, and multiple requests can be made. Where the old stack used 30 servers, the new one uses just three for all of LinkedIn’s mobile traffic.

On the client side, the mobile team used HTML5 to implement most app features. There are some parts of the apps, though, such as the infinite stream list, that are native because, Prasad said, they don’t perform well in HTML5. Performance optimization was the reason his team has recently pulled back a bit from HTML5, taking the new iPad app from around 95% HTML5 to about 90% now.

Looking toward the future, Prasad said his team is nearly done with its first of three steps, which is making LinkedIn available on all mobile platforms. He stated that they still have a couple of phone platforms to go, and that more will be done for other tablets in the future.

The second step, enabling use, is the one the LinkedIn mobile team is currently working on. This step sees the team optimizing their apps and creating a better user experience overall.

While working on these first two steps, LinkedIn has gained enough confidence in mobile to begin experimenting with monetizing its apps. LinkedIn CEO Jeff Weiner last month stated that ads would soon become part of its iPad app, and that premium subcriptions for mobile are a possibility. LinkedIn has, in fact, now begun experimenting with ads in its LinkedIn app, though they are testing the move carefully with only a couple of advertising partners.

Prasad said much the same during our interview. He and his team “definitely” don’t want the new ads to impact the user experience, and are being cautions while gathering metrics on the few current ads. Prasad said that subscriptions for premium mobile features are a natural progression of LinkedIn’s business model that will eventually make their way to mobile.

The third step for LinkedIn’s mobile engineering team, as described by Prasad, is more of a leap. He states that he wants to make the mobile team a leader, and contribute back to LinkedIn the way other teams have contributed to mobile. Obviously this third step is more of a long-term goal, but Prasad seemed confident in his team and in LinkedIn as a whole. “This happens to be one of those great, lucky environments.”