Hammerspoon

Hammerspoon is a macOS automation tool that connects the operating system to a Lua scripting engine. It solves the problem of writing custom system-level automation by exposing macOS APIs through extensions, allowing users to write Lua code that interacts with applications, windows, mouse pointers, filesystem objects, audio devices, batteries, screens, low-level keyboard and mouse events, clipboards, location services, wifi, and more. Users typically write a Lua configuration file in ~/.hammerspoon/init.lua that connects events to actions, such as binding keyboard shortcuts to window operations, running commands when a wifi interface connects, or displaying alerts based on battery level.

Hammerspoon includes extensions that expose specific pieces of system functionality, along with pre-made plugins called Spoons. The project provides a Getting Started Guide, full API Documentation, and Release Notes for compatibility with different macOS versions. Extensions can be written as pure Lua scripts offering helper functions, or as Objective-C extensions that expose new areas of system functionality. Hammerspoon is distributed as a downloadable macOS application that users install by dragging it to /Applications/. The project is open source, with contribution guidelines and an issue tracker available on GitHub, and community support through a Discord server.