National Center for Missing and Exploited Children: Check this site for information about harmful apps and much more helpful tips.
Educate Empower Kids: Find the most dangerous apps for 2017 here.
Megan Maas: app guide for parents available here
Common Sense Media: Parenting, media, and everything in-between.
Common Sense Media also has helpful information to help you take action if your think your child is being bullied online. Click here.