WhatsApp announced on its blog last week that it has unveiled a desktop version for Android users. They can access it by scanning a QR code on a webpage with their phone, which must remain connected to the internet.
"Our web client is simply an extension of your phone: the web browser mirrors conversations and messages from your mobile device - this means all of your messages still live on your phone," the post said.
The app has never sold ads, a philosophy which co-founder Jan Koum explains in this blog post.
One possible implication is that Facebook, which last year acquired the messenger service for US$19 billion, could collect more behavioural data to serve better targeted ads.
WhatsApp's terms and conditions states it does not retain delivered messages and the only records of those messages are stored in the sender and the recipient's mobile devices and can be deleted by the users.
In another blog post, Koum wrote, "Respect for your privacy is coded into our DNA, and we built WhatsApp around the goal of knowing as little about you as possible: You don't have to give us your name and we don't ask for your email address. We don’t know your birthday. We don’t know your home address."
"We don’t know where you work. We don’t know your likes, what you search for on the internet or collect your GPS location. None of that data has ever been collected and stored by WhatsApp, and we really have no plans to change that."
Koyi Wu, associate director at Airwave, said it is illegal to collect data about people's private conversations but this may not extend to behavioural data.
"Any mobile app can install a software development kit in the back-end that can track in which city the user was when they downloaded the app, what website they visited or banner they clicked on before downloading the app and after they installed the app, what website they visited before opening the app," Wu said.
If Facebook matches user behavioural data from Facebook and WhatsApp, such as using cell phone numbers, it could create a wealth of data about user interests across the two platforms on mobile, and now desktop.
"WhatsApp is not recording the exact users' conversations, which is illegal. What WhatsApp can do is understand users' interests through their software development kits and ride on those interests to serve more relevant ads on Facebook," Wu said.
The point of launching a desktop version for WhatsApp is to learn about users' interests across screens.
"Facebook is able to do cross-screen marketing on the market because it has lots of login data - you would be logged into Facebook on your smartphone, tablet and desktop and you would rarely log out," Wu said.
"This increases the scope of behavioural data they can collect. For example, if I'm a foodie and I browse lots of food-related websites before opening or chatting on WhatsApp on desktop, then they could show me more food-related ads when I use Facebook."
She added that desktop matters because people use different screens for various purposes.
In admanGo's 2014 report, mobile's share of adspend in Hong Kong stands at 2% compared to 8% for websites accessed on PC.
Kevin Huang, CEO of Pixels, agrees, saying multi-screen is the future rather than mobile-first or mobile-only.
"Ads are not on the deck for WhatsApp. It's possible that Facebook wants to collect behavioural data to inform Facebook advertising," Huang said.
WhatsApp has begun introducing stickers. Will they take the route as mobile apps WeChat and Line?
While Line charges brands for stickers and official accounts, WeChat allows brands to open official accounts for free but would charge for sponsored content and mobile payment solutions.
"My gut feeling is that WhatsApp won't be like WeChat and Line. Facebook's way is more sustainable in the long run because any form of ads are very annoying in instant messaging apps. Facebook probably wouldn't give you ads directly on Whatsapp," Wu said.
"It makes more sense to serve the ads on Facebook using learnings from WhatsApp because people are used to seeing ads on Facebook now."