How to Capture a Mac Window Without Its Drop Shadow

Step by step

1. 10 sec

   Switch to window capture mode

   Press Command + Shift + 4. The pointer becomes a crosshair. Press the Space bar and the crosshair becomes a small camera. Move it over any window and that window highlights. Click and only that window is captured, cropped to its own edges.

   Note: Space toggles back to the crosshair if you change your mind. Escape cancels the whole thing without saving anything.
2. 5 sec

   Hold Option as you click

   With the camera pointer over the window you want, hold Option and click. The window is captured with no shadow and no transparent margin around it. The file is smaller and the image edges sit exactly on the window edges.

   Note: Hold Option before the click, not after. Release it a fraction early and you get the shadow back, with no warning that you did.
3. 1 min

   Disable the shadow permanently

   Open Terminal from Applications > Utilities. Type defaults write com.apple.screencapture disable-shadow -bool true and press Return. Then type killall SystemUIServer and press Return. Window captures from that point on arrive with no shadow, no modifier key required.

   Note: The killall line restarts the process that draws the menu bar. The screen blinks once. Nothing is lost and no reboot is needed.
4. 1 min

   Reverse the change when you need it

   Run defaults write com.apple.screencapture disable-shadow -bool false, or remove the key entirely with defaults delete com.apple.screencapture disable-shadow. Follow either one with killall SystemUIServer. The shadow returns on the next capture and the Option key behaves as it did before.

   Note: Deleting the key is cleaner than setting it false. One leaves nothing behind. The other leaves a preference nobody will remember writing.
5. 10 sec

   Check the result before you use it

   Select the capture in Finder and press the Space bar. A shadowed window screenshot shows a soft grey halo on all four sides against the Quick Look background. A clean one stops at the window corners. Look at it before pasting it into anything.

   Note: The shadow is transparent, not white. It hides on a white page and reappears the moment somebody opens that document in dark mode.