AutoIt  is a freeware programming language for Microsoft Windows. In versions 1 and 2, it was used to create automation scripts for Microsoft Windows programs. These are sometimes called macros. In version 3, the programming language was extended to allow it to do more things.

The scripting language in AutoIt 1 and 2 was statement-driven. It was designed to simulate a user's input to the computer. From version 3 onward, the AutoIt syntax changed. It is now similar to the BASIC programming language. AutoIt version 3 is a general-purpose  programming language. It can have types of data, such as arrays.

An AutoIt script can be converted into a stand-alone executable. This can be run on computers that do not have the AutoIt interpreter installed. A wide range of function libraries are available. They are known as UDFs, or "User Defined Functions". Some are included as standard. Others are available from the website. They add extra abilities to the language. AutoIt has a special editor, an Integrated development environment or IDE. It is based on the free SciTE editor. The compiler and help text are included in this special editor and provide a standard environment for developers.

Features
 Scripting language with BASIC-like structure for Windows
 Compiling into standalone executables
 Add-on libraries and modules for specific applications or apps
 Supports TCP and UDP protocols
 Supports component object model (COM)
 Call functions in DLL files
 Run console apps and access the standard streams
 Include data files in the compiled file to be extracted when running
 Create graphical user interfaces, including message and input boxes
 Play sounds, pause, resume, stop, seek, get the current position of the sound and get the length of the sound
 Simulate mouse movements
 Manipulate windows and processes
 Automate sending user input and keystrokes to apps, as well as to individual controls within an app
 Unicode support from version 3.2.4.0
 64-bit code support from version 3.2.10.0
 Supports regular expressions
 Compatible with User Account Control
 Object-oriented design through a library

Usage
AutoIt is often used to produce utility software for Microsoft Windows. These programs can automate routine tasks. Example use includes: systems management, monitoring, maintenance, and software installation. It is also used to simulate user interaction. In this use an application is "driven" to do things by an AutoIt script which behaves like a human user. An AutoIT script can issue keypresses, mouse clicks, type text and so on. In this way it simulates a human user of an application.

AutoIt has been used in low-cost laboratory automation. Applications include instrument synchronisation, alarm monitoring and results gathering. Devices such as 3D-printers can also be controlled.

Examples

Hello world
<syntaxhighlight lang="autoit">
 Make available a library of constant values.
include <MsgBoxConstants.au3>

 Displays "Hello, world!" in a messagebox.
MsgBox($MB_SYSTEMMODAL, "Title", "Hello, world!")
</source>

Automating the Windows Calculator
<syntaxhighlight lang="autoit">
 Make available a library of constant values.
include <MsgBoxConstants.au3>

 Display a message box with a timeout of 6 seconds.
MsgBox($MB_OK, "Attention", "Avoid touching the keyboard or mouse during automation.", 6)

 Run the Windows Calculator.
Run("calc.exe")

 Wait for the calculator to become active with a timeout of 10 seconds.
WinWaitActive("[CLASS:CalcFrame]", "", 10)

 If the calculator did not appear after 10 seconds then exit the script.
If WinExists("[CLASS:CalcFrame]") = 0 Then Exit

 Automatically type the current year into the calculator.
Send(@YEAR)

 Let's slow the script down a bit so we can see what's going on.
Sleep(600)

 Automatically type in 'divide by 4', and then sleep 600 ms.
Send("/4")
Sleep(600)

 Hit the return key to display the result, and sleep 600 ms.
Send("{ENTER}")
Sleep(600)

 Copy the result to the clipboard using the Windows shortcut Ctrl+C.
Send("^c")

 Declare, and assign the contents of the clipboard to, a variable.
Local $fResult = ClipGet()

 Check to see if the variable contains a decimal point or not.
If StringInStr($fResult, ".") Then
    ; Display a message box with a timeout of 5 seconds.
    MsgBox($MB_OK, "Leap Year", @YEAR & " is not a leap year.", 5)
Else
    ; This message will only display if the current year is a leap year.
    MsgBox($MB_OK, "Leap Year", @YEAR & " is a leap year.", 5)
EndIf

 Close the Windows calculator - always tidy up afterwards.
WinClose("[CLASS:CalcFrame]")
</source>

Find average
<syntaxhighlight lang="autoit">
 Find Average by JohnOne, modified by czardas
include <MsgBoxConstants.au3>

_Example() ; Run the example.

Func _Example()
    ; Display an input box and ask the user to enter some numbers separated by commas.
    Local $sInput = InputBox("Find Average", "Enter some numbers separated by commas: 1,2,42,100,3")

	; If an error occurred then exit the script.
	If @error Then Exit

    ; Populate an array with the user's input.
    Local $aSplit = StringSplit($sInput, ",")

    ; Pass the array to the function _Find_Average() and then check for errors.
    Local $fAverage = _Find_Average($aSplit)
    If @error Then Exit

    ; Display the result in a message box.
    MsgBox($MB_OK, "Find Average", "Result: " & $fAverage)
EndFunc   ;==>_Example

Func _Find_Average($aArray)
    ; If the input is not of the correct type (an array), then return an error along with the details.
    If Not IsArray($aArray) Then Return SetError(1, 0, VarGetType($aArray))
	; More detailed checks are possible, but for brevity just one is performed here.

    ; Declare a variable to store the sum of the numbers.
    Local $iArraySum = 0

    ; Loop through the array.
    For $i = 1 To $aArray[0]
        ; Increment the sum by the number in each array element.
        $iArraySum += Number($aArray[$i])
    Next

    ; Return the average rounded to 2 decimal places.
    Return Round($iArraySum / $aArray[0], 2)
EndFunc   ;==>_Find_Average
</source>

History
 January 1999 - First AutoIt Version (1.0)
 August 1999 - AutoIt v2 and AutoItX
 September 1999 - First AutoIt version with Compiler
 December 2002 - AutoIt v3 (Public Beta)
 February 2004 - AutoIt v3 (Stable)
 September 2006 - Auto3Lib started
 November 2007 - AutoIt v3.2.10.0 released, Auto3Lib incorporated into AutoIt v3
 May 2008 - AutoIt v3.2.12.0 released, incorporating added GUI functionality
 December 2008 - AutoIt (and AutoItX) v3.3.0.0 released
 December 2009 - AutoIt v3.3.2.0 released
 January 2010 - AutoIt v3.3.4.0 released
 March 2010 - AutoIt v3.3.6.0 released
 April 2010 - AutoIt v3.3.6.1 released
 December 2011 - AutoIt v3.3.8.0 released
 January 2012 - AutoIt v3.3.8.1 released
 December 2013 - AutoIt v3.3.10.0 released
 June 2014 - AutoIt v3.3.12.0 released
 July 2015 - AutoIt v3.3.14.0 and v3.3.14.1 released
 September 2015 - AutoIt v3.3.14.2 released
 February 2018 - AutoIt v3.3.14.3 released

License
The developers of AutoIt originally released the source code under the GNU General Public License (GPL). 

In 2006, the license was changed for version 3.2.0 and later versions to their own closed source license.

Some of the code from version 3.1 was used to create a fork by the AutoHotkey project. This was allowed under the GPL licence terms. The AutoHotkey community is continuing to develop and release the code under the GPL.

References

Other websites
 Official AutoIt website

Programming languages