[Closed] Kinzoo - Family Chat alternatives.

Installed Kinzoo a couple of weeks ago for the immediate family to contact our young kids direct and (perhaps surprisingly) it's been superb.

Problem is there's no web interface which is a deal breaker when trying to include one grandparent.

So what's the alternative?

Requirements:
1) No phone number required.
2) Web interface and/or windows app & Android App.
3) Ideally I only want named people to initiate contact my kids but that's not a deal breaker, they are young enough that we supervise their use very closely.
4) Free 🙂

Given 3) a lightweight chat app of any kind would probably work.