While the number of, and power of, native Keyboard Maestro Actions is vast, sometimes you may need to do something that Keyboard Maestro is not well suited to do. But Keyboard Maestro has anticipated, and provided for this, by providing a number of Execute Script Actions, all of these available from the Execute category in the Action List:

For example, the Execute_an_AppleScript Action:

Note that the script can be either embedded in the Action, or in an external script file, linked using the Execute Script File choice.

The Actions for the other script languages are very similar.

For more details about scripting, see the User Manual Page on Scripting

• AppleScript – Using Keyboard Maestro Variables in AppleScript.
• Execute an AppleScript action.

• Execute a JavaScript For Automation action – shows how to get/set Variables.
• Execute a JavaScript in Safari action.
• Execute a JavaScript in Google Chrome action.
• Execute a JavaScript in Custom Prompt action.
• JavaScript for Automation – Provides an introduction to JXA and comparison with AppleScript.
  

• Execute a Shell Script action.

• Execute a Swift Script action.

• Execute an Automator Workflow action

• Scripting the Keyboard Maestro editor
• Scripting user manual section

• Create Text Expansions Macro
• Create Text Expansion From Selection Macro
• Add the contents off the clipboard as a Unicode expansion to Typinator
• Keyboard Maestro Forum topics about Scripting