Facebook messenger lite app for Android is a must have app for people that want to chat on Facebook and still save data, RAM and battery. It is ideal for low end devices with 1GB RAM or less and slow Internet connection.
The app of course removes some extra features in order to stay lite. But if you really want to save data you won't mind that.
You can search the Google play store for "messenger lite" or Click Here to download the apk. The apk file size is just 4mb.