While the U.S. has the ESRB rating system, mostly for games, it is completely optional. That's also true for the PEGI system that's used in most European countries and the CERO system in Japan. However, four countries (Brazil, Russia, Korea, and Taiwan) do require that apps submitted to the local Windows Store or Windows Phone Store get a rating from their respective systems.
Even if an developer is submitting an app in a store that does not require a rating, Microsoft does recommend that they go ahead and put the app through the appropriate optional system, stating, that "this will provide an assurance to your users that the content is appropriate for the age group, and helps protect children from content inappropriate for their age." There is a free online tool that Microsoft provided for both the ESRB and PEGI systems.
For Brazil, which requires the use of their DJCTQ rating system for apps, Microsoft says there are three ways to obtain that rating:
- Submit your game for review by the DJCTQ, and get a rating published in the official government publication
- Obtain a ESRB game rating using the online form (Windows or Windows Phone), and then you assign the equivalent rating using DJCTQ guidelines
- Obtain a PEGI game rating using the online form (Windows or Windows Phone), and then you assign the equivalent rating using DJCTQ guidelines
Microsoft also offers tips on obtaining ratings for Russia as well as other countries. Why do you think about Windows Phone and Windows 8.1 apps requiring a rating in some countries and not in others?