SPIN Browser is definitely the best solution for letting your kids surf the web freely on Android. I tried them all and this is the most simple and effective solution.

This is a brilliant app which is excellent at blocking inappropriate content.

Personally I think I like it better than Google.

Really perfect. The best browser with the best filtering. It is really safe to use. It is the best browser I've ever had and is build upon Firefox, which gives you a way better experience than Chrome on mobile.