The 1.1 version of HeadlessScreenChanger 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.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The actual developer of this free Mac application is BeNiceGames. The software lies within Developer Tools, more precisely Webmaster Tools.
From the developer:
Headless Screen Changer helps you change the screen resolution for you to use with your favorite screen sharing utility and maximize the screen real estate of your headless Mac mini. While Headless Screen Changer was designed for the Mac mini owner in mind, any MacOS device will work too.
You may want to check out more software for Mac, such as Boks, Navicat for Oracle or GoodPage, which might be similar to HeadlessScreenChanger.