WowAce

Creates and manages secure Action Buttons

Tracks rare drops, including companions and mounts

Modular casting bar.

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

A library to help with localization of in-game subzone names.

Provides one or many frames for dumping text into.

A skinning engine for button-based add-ons.

Restores access to removed interface options in Legion

The original source for where things are in Pandaria

Arena unit frames

A library to help with localization of the output of UnitCreatureType.

Show item levels in the character frame

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

"Debug" code free since '93!

Adirelle's bag addon.

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

A library to help with localization of races.

Shared handling of alternate identity data between addons.

Replacement for the default UI's StaticPopup dialogs.

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