Which version of GIMP works well with MacOS 10.12 Sierra? Current version is 2.8.18 but, I read that the last stable version that works with Sierra is 2.8.14. https://www.gimp.org Is GIMP blocked from installing due to being an unknown developer? That is what I get when try to open the dmg. I thought the way around this black was to go to System Preferences/Security & Privacy/General Tab and change the setting from allow apps downloaded from App Store & identified developers to allow from anywhere. http://osxdaily.com/2016/09/27/allow-apps-from-anywhere-macos-gatekeeper/ Requires enabling that 3rd choice using Terminal command.