Website Utilities

WebLua - Interactive web-based Lua interpreter.

BLP2PNG - Convert BLP files to PNG and vice versa.

Blizzard artwork browser - Allows you to view the textures included in World of Warcraft in PNG format on the web

Blizzard FrameXML browser - Shows you comparisons between the live and any development version of Blizzard's FrameXML code. Also allows you to view individual files easily.

XML Validator - Validates your XML files, showing any errors you might have made when constructing them.

Helper Applications

AddOn Studio for World of Warcraft (not actively supported) - A Visual Studio-like IDE for developing WoW addons

Interface Customization Tool - Official Blizzard UI kit. Extract all the built-in interface files including source code and artwork.

Lua-WoW (PC Zip, Mac DMG) - Modified Lua distribution that includes changes to more closely match the WoW environment. See the readme files for more details.

Development Addons

WowLua - In-game Lua scripting environment. Includes an interactive interpreter, and a multi-page script editor. Available for download at WoWInterface.com.

DevTools - This addon lets you examine API events as they fire, lists all the frames underneath the mouse, and provides a few other handy slash commands for developers.