Facebook Messenger Kids is now available on the US Amazon Appstore for Amazon Fire tablets.
Facebook Messenger Kids is specially designed for children under 13, who are too young to have their own Facebook account.
It lets them send messages and hold video calls with a list of contacts approved by their parents.
Parents must download the app to their kid's phone, authenticate the device with their own Facebook account, and set up a profile with the child's full name. Contacts can only be added to the app via Facebook itself, so it's up to parents to decide who their kids can speak to.
If a child wants to speak to one of their classmates, for example, their parents have to link the two Messenger Kids accounts on Facebook itself. The connection has to be mutually agreed before the kids can start talking.
Adult friends and family members can use the regular Facebook Messenger to chat with youngsters on Facebook Messenger Kids, provided the link has been approved by the parents.
Facebook Messenger Kids accounts aren't publicly searchable, and the app doesn't display ads or gather data for advertisers.
A version of the app for Android devices is expected at the end of January.