please see the list below for required/suggested addons. Some are required (few) and some are just suggestions.
It is a useful damage meter, but that is not the reason why it is required. It is required because of the threat meter.
"GTFO provides an audible alert when you're standing in something you're not supposed to be standing in."
*note you do not have "use it" but it has to be installed and active. This allows other healers to see your incoming heals. Ideally you should use something, but it is up to the healer.
suggestioned settings for healbot. Shut off arrows, show mana bars, setup lower ranked spells.
CharacterStatsClassic is an addon for WoW Classic which displays more character stats than the default WoW's interface. (like hit!)
This is a mod to make swapping equipment easier through popout slot menus, equip slot buttons, gear sets and automated swaps.
"Beyond the basic all-bags-in-one functionalit"
Auto sells you trash items
Better Vendor Price
shows the vendor price for items when you mouse over it.