For many years, GIMP didn't have native macOS support (you needed X11 to make it work). Seashore wasn't as fully featured as GIMP, but it was native. As of Sierra (macOS 10.12), Seashore just crashes when you try to launch it. R.I.P., Seashore.
Fortunately, if you're looking for a free alternative to Photoshop, GIMP is still around, and it's now native to macOS.
2 replies on “Seashore breaks with Sierra; use GIMP (or Photoshop) instead”
[…] feature from software is changed, drivers not available anymore, software is not working with a new OS, sometimes new OS is slower than old one, […]
Seashore is back and working on the latest OSX releases. You can find it on the App Store – and it’s FREE !
https://geo.itunes.apple.com/us/app/seashore/id1448648921?mt=12&app=apps