Here is a useful parents page here with lots of ideas for families, and a section for under 7's.
There is a 5 star FREE app on the apple store and the App store.
Here is the link to the Apple version
Here is the link to the Android version
There is an excellent app where parents can control the amount of screen time a child has access to, and has a locator feature.
This is Our Pact and details can be found here: