Safe for most kids
Skype is a video-conferencing app that also supports instant chat messaging and voice calls.
Social Networking
Photo & Video

In-depth breakdown

Minimum Age Requirement
Messaging Capabillities
Skype allows individual and group video calls, instant messaging, and even calls to landlines (though with fees). Calls need to be added as contacts through an email, phone number, or name search.
Location Sharing
Parental Controls
Skype is owned by Microsoft, and within a Microsoft family account, parents can limit screen time, establish filters, and block app usage. Apple and Android parental controls can be used at the device level.
You can make yourself unsearchable in Skype, so that no one can contact you unless you reach out to them directly.