A new app can help alert parents if their kids are sexting. The free app, released Tuesday on Android and iPhone, is called Gallery Guardian.

Here’s how it works. Parents have to download the app to their phone as well as their kid’s phone. The app scans the child’s photo gallery for inappropriate pictures, such as a nude photo. If it detects the child has saved one, the parent gets an alert on their phone. There’s also a setting to detect less graphic pictures, such as lingerie or swimwear.

The alert to the parent does not show the actual photo itself, in order to respect the child’s privacy to some degree.

The app will scan 25 pictures for free. After that, parents can pay for a monthly subscription.

It is possible kids can delete the app. However, parents will receive a notification if that happens.