An AU3 file is an automated script file created with the freeware scripting program, AutoIt v3. It contains the AutoIt3 scripting language for automating commands within Windows. AutoIt3 programming language lets you simulate a number of events that can be used to automate tasks. For example, the script inside AU3 file can be used to simulate keystrokes, mouse movement, controlling windows position and other scripting purposes.
Applications that can open AU3 files include SciTE4AutoIt3 and AutoIt.
AU3 File Format
AU3 files are saved as text files and contain AutoIt3 scripting language.