Facebook messaging app

[marios1441]

I'm looking for a messaging app for Facebook's inbox for slow phone that uses very little ram with size up
to 6MB maximum that also shows notification and plays sound (selectable from phone's message sounds if
possible) when a new message arrives even when the app is not open.

 

[SpookDroid]

Once upon a time there was Trillian, but not even sure if those 3rd party IM clients are even still in existence or being developed. In your case you might be better off using Chrome's push notifications and using Facebook's messenger page (www.messenger.com). I don't think you can select a specific ringtone for that page (you can select a general notification ringtone, but that will affect every generic notification in your device), but you can receive notifications from the browser.