The 4.7.5 version of InjectionIII for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This free software for Mac OS X was originally developed by John Holdsworth. We recommend checking the downloaded files with any free antivirus. The program is categorized as Developer Tools.
From the developer:
InjectionIII adds a "Hot Reloading" capability to your iOS, tvOS, and macOS projects written in Swift or Objective-C. This allows you to change the implementations of methods, functions, and SwiftUI body properties without having to restart your app for rapid iteration over minor code changes and design.
You may want to check out more Mac applications, such as Navicat for Oracle, Cocoa Browser Air or BLT, which might be related to InjectionIII.