Besides chatting with friends and idly thumbing through their social feeds, you can now buy luxury bags off China's largest social app, WeChat.

The country's most popular messenger app -- which boasted nearly 900 million daily users last year -- is so ubiquitous that luxury brands like Longchamp and Burberry are jumping onboard, reports the Wall Street Journal.

Big brands like Louis Vuitton, Givenchy and Dior are also testing demand through flash sales.

Early adopter, Longchamp, has already launched two in-app stores. One allows people to create customised products from the French maker, and the other allows people to post their experiences with Longchamp's physical stores.

"We've seen the importance of WeChat," Jean Cassegrain, Longchamp's CEO, told Interface, a Chinese tech publication. The company found that WeChat pulled in a lot of sales, after earlier experiments with social media marketing in China.

WeChat seemed more effective than other e-commerce platforms, Cassegrain added. "One way or another, [WeChat] will significantly contribute to our sales."

WeChat is taking over everything

This validation for WeChat is a big deal. The app started out as a messenger before adding a Facebook-style timeline feature, allowing people to blast their lives to friends.

Today, you'd find WeChat's in-app wallet commonly used for transferring money to friends, as well as paying merchants of all sizes, from roadside stalls to big retail stores. This payment is often done by scanning a simple QR code.

But will that spending translate to big ticket items from luxury brands? That remains to be seen, say industry watchers.

Pablo Mauron, managing director in China for Digital Luxury Group, a high-end digital marketing firm, said: "For the luxury industry, it's important not to fool ourselves...People want to touch the product."

"I'm still doubtful that someone that doesn't have a relationship with a brand will buy a $20,000 watch on WeChat."

Still, brands setting up WeChat stores creates a unique closed loop not seen in many other examples outside of China. This loop takes users from the initial contact with the brand, to the purchase, and straight through to a personalised customer service channel, observed Interface.