WowAce

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

an embeddable library providing an abstraction layer for tracking and querying Blizzard's Nameplate frames with ease and effi...

Library that tracks incoming heals

Database of Diminishing return categories and general data

Shared handling of alternate identity data between addons.

Libra

Provides data about all artifacts in the player's possession.

LibItemInfo-1.0

A powerful, comprehensive utilty for displaying graphics and information based on buffs, debuffs, and other triggers.

Library providing mappings between trade skill recipes, spells and created items

Test whether the player can really dispell a buff or debuff, given its talents.

A library to handle rearrangement of blizzard's frames when bars are added to the sides of the screen.

Utility library with shared functions and data for various addons by NeoTron.

Simple library that handles multiple levels of logging.

Modular casting bar.

Displays additional information for Mythic Keystone dungeons

Simple and Advanced combined - Bartender4 ActionBar AddOn

Inserts some media into LibSharedMedia's storage.

Postal: Enhanced Mailbox support

Afflictions display and cleaning for solo, group and raid with advanced filtering and priority system.