Users worry that their privacy could be breached by an app called “Xiguazuji” (Watermelon Footprint), according to a report by Modern Express on Sunday.

Some users are concerned that their information could be used for other purposes by the company. However, Dai Hongmin, cofounder of the app, told Modern Express that users should not worry about privacy issues as the app didn’t collect or store user data.

The app, which was launched less than one week ago, recorded more than 10 million views by June 1, according to a post on Dai’s WeChat moments.

After scanning the QR code of the app, users can choose the cities they have visited, then a footprint map will be generated, together with a number showing how many percent of users they have surpassed.

However, the popular app needs some tweaking. For instance, it is hard to tell whether users have been to those places they claim since big data analytics hasn’t been used in the app.