The app made headlines recently for its ability to instantly connect people with a significant amount of information about complete strangers—or people they know—by uploading a single photo. With the app, all you have to do is take a photo of someone and upload it and you will be able to see other photos of that person—photos that you did not necessarily take. You’ll also be able to see where those photos were uploaded, according to an article from The Chicago Tribune.

The app is anchored to a database of more than 3 billion images that the firm claims it scraped from the web—places like Facebook, YouTube and countless other websites. Law enforcement is currently using the app to help solve crimes.

However, the app has a significant number of detractors. Wired, for its part, called the app a “nightmare scenario” for privacy advocates. “Like almost any tool, scraping can be used for noble or nefarious purposes,” according to the Wired article. The article further notes Facebook and Twitter forbid automated scraping of its content.

For marketers, the challenge is always striking the right balance between using groundbreaking technology like this to collect information about customers and potential customers that allows the effective targeting of products and services to likely buyers. The challenge is to do so in a way that is not seen as overstepping. Customers are generally creeped out when they feel they are being electronically stalked by a brand or marketer.

Additionally, collecting or using large amounts of personal data comes with its own host of challenges, as illustrated by the Facebook-Cambridge Analytica scandal. Future developments in this story may have big regulatory implications for data collection and use in the marketing industry. It is worth keep an eye on it.