Is there a system API, or utility (open source), or default I can set to disable all 4 rounded window corners on macOS?

I've checked the two other prominent questions relating to this:

  1. Can I change 10.8.2 Mountain Lion window corners from rounded to squared?
  2. How can I disable rounded window corners in OS X

And the links are either dead, or the offered solution does not work.

  • 2
    I don't know for absolute certain, so can't provide an actual answer, but basically DIY custom theming hasn't been possible on Mac in the past decade.
    – Tetsujin
    Sep 24, 2019 at 11:28
  • I know that the radius is possible for NSWindowStyle or something to that effect, it seems a bit heavy if it is impossible to not change the window radius to 0 though :(
    – tsujp
    Sep 25, 2019 at 6:07

1 Answer 1


I figured it out, I used ThemeEngine to edit the appropriate theme in SystemAppearance.bundle.

I made a repo with the changes here: https://github.com/tsujp/custom-macos-gui

I know StackExchange hate linking answers so here is a summary for my case:

  1. Using ThemeEngine edit the files in DarkAquaAppearance.car
  2. The files you need to edit are WindowFrame_WindowShapeEdges
  3. Change the masks to squares.
  4. Change the base to completely transparent.
  5. Reboot or otherwise restart the Dock, Finder, SystemUIServer, etc.


  • Care to add a screenshot? I'm curious how this looks.
    – Dillon
    Oct 11, 2019 at 15:49
  • 1
    @Dillon I added the screenshot in my repo to my self-answer, give it a check
    – tsujp
    Oct 11, 2019 at 16:18
  • This works great on Mojave, and also on Catalina. However, on Big Sur, I'm not able to find WindowFrame_WindowShapeEdges when I open the file in ThemeEngine. How can I fix the corners in Big Sur+? Nov 8, 2021 at 20:07
  • I'm still waiting for my M1 machine to arrive at which point I can continue work on this and make a little single-binary configuration tool too. Until then I am not sure (no macOS machine to play around it, and VMs are a poor experience)
    – tsujp
    Feb 7 at 7:36

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