The 3.1.0 version of GB Studio 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 Mac app is an intellectual property of Chris Maltby. We recommend checking the downloaded files with any free antivirus. GB Studio for Mac lies within Games, more precisely Tools.
From the developer:
GB Studio is a quick and easy-to-use drag-and-drop retro game creator for your favorite handheld video game system. The inbuilt editor makes writing music easy. The tool provides both piano roll and tracker modes. You can create real ROM files and play on any GB emulator. You can export for web with great mobile controls, upload to Itch.io and share your game with the world.
You may want to check out more software for Mac, such as 3D Sketch and Stretch Studio, Glyphr Studio or iSkysoft DVD Studio Pack, which might be related to GB Studio.