WowAce

Database of item upgrade IDs

Arena unit frames

A skinning engine for button-based add-ons.

Library that handles chat output.

Simple AceGUI3 dropdown item classes for font/statusbar/sound/etc.

"Debug" code free since '93!

Officially the original source of knowledge of where things are in Draenor during Warlords, in HandyNotes

Replacement for the default UI's StaticPopup dialogs.

Parses ToC and adds About panel to Interface options

The original HandyNotes source for where things are in Battle for Azeroth

Allows you to view all items from all your characters on the same account, when-ever and where-ever you want.

Another HUD addon

Modular damage meter.

Library to check whether an item is equipable / appropriate for a given class

Collects Herbs, Mines, Gas Clouds, Archaeology, Treasure and Fishing locations and adds them to the worldmap and minimap

Adds a Button to the Worldmap which toggle Handynotes

In World of Warcraft healers have to die. This is a cruel truth that you're taught very early in the game. This add-on helps you influence this unfortunate destiny in a way or another depending on the healer's side...

Replacement for ActionButton_Show/HideOverlayGlow APIs

An intuitive keybindings library.

Creates and manages secure Action Buttons