is a powerful scripting language by Chris Mallett. It allows manipulation of applications' windows, easy definition of hotkeys and auto-replace hotstrings, user-defined functions, UI creation (with standard Win32 controls), and a lot more.
Development has been stopped.
is a custom version of the AutoHotkey scripting language, developed by Lexikos (Steve Gray). It is based on the original AutoHotkey source code and adds features such as Array / Object support, Unicode, 64bit support, native COM and a lot more. AutoHotkey scripts should be compatible to AutoHotkey_L in most cases, except for some encoding issues and variale names using reserved characters.
AutoHotkey_L is actively developed.
AutoHotkey v2 (AHK v2)
is the next version of the AutoHotkey scripting language, developed by Lexikos (Steve Gray) and based on the AutoHotkey_L source code. It will clean up syntax, (hopefully) simplify things, and make more use of Array / Object features. Unlike AutoHotkey_L, it will contain many breaking changes.
AutoHotkey v2 is actively developed, but it is still in alpha stage.
is another custom version of the AutoHotkey scripting language, developed by polyethene / Titan, running on .NET. It represents a from-scratch rewrite, but also adds some features, such as Array/Object and Unicode support. The goal is to be able to run AutoHotkey on any system, and to compile it into .NET assemblies.
Unluckily, development seems to be paused for some time now.