Dimma Screen · Lock your Mac, keep the screen on

Step away and Dimma Screen covers every display with a tint you can barely see. Your desktop stays lit and keeps moving, so it looks like you’ll be right back. Touch a key or the mouse, and it asks for your PIN.
All features free for 3 days · macOS 26 Tahoe or later · Apple silicon
The macOS lock screen goes dark and puts up the login window. Anyone walking by can tell you’ve gone. Dimma Screen leaves your desk the way it was and keeps your work out of reach.
Menu bar › Turn On and Keep Awake
Choose 30 minutes, 1 hour, 2 hours, or 4 hours. The display stays lit and your Mac stays awake, so downloads and builds keep running.
When the time is up, your Mac follows its usual energy settings again. The cover stays, and it still takes your PIN to get back in.
Leaving for longer? Turn on Lock Screen When Keep Awake Ends in Settings. When the time runs out, Dimma Screen hands over to the macOS lock screen. It works however the overlay was turned on.
Settings › Display › Show
A faint tint over your live screen. Video keeps playing and the clock keeps ticking. Set it anywhere from 2% to 50%.
One color on every display. Nothing on screen shows through.
Your screen exactly as it looked when the overlay turned on. It stays in memory and is cleared when you dismiss the overlay. Needs Screen Recording access.
A picture of your choice, scaled to fill each display.
A little motion against burn-in. Pixel Shift, Breathing Brightness, and Gradient Drift keep the picture from sitting still. At Subtle, the default, Pixel Shift moves a snapshot or image 2 points every 45 seconds. Pick a stronger setting if you don’t mind people noticing. With Reduce Motion on, nothing moves.
Menu bar › Turn On with Away Note
Write one line, like “Back in 5” or “This room is taken.” It shows on every display with the time you’ll be back. One click turns on the overlay, keeps the screen on, and puts up the note.
Touch the keyboard or mouse and a small glass panel fades in on the display under the pointer. Type your 4- to 8-digit PIN. The overlay goes away the moment the last digit is right. There are no buttons to find.
Covers every display, every Space, and full-screen apps. A display you plug in while the overlay is on is covered too.
Turns on after 5, 10, 20, or 30 minutes or an hour without input. Or set your own keyboard shortcut.
The app, its process, and its windows are named just Dimma. Until someone touches the Mac, the menu bar keeps showing the app you were using.
Only a salted hash of your PIN is kept, in your login keychain. Snapshots stay in memory and are cleared when you dismiss the overlay.
If macOS locks the screen while the overlay is on, Dimma Screen steps aside. Unlock your Mac as usual and you’re back, with no PIN to type.
English, 简体中文, 繁體中文, 日本語, 한국어, Deutsch, and Français. It follows your Mac, or you can pick one in Settings.
No. It doesn’t move the pointer or type for you. It keeps the display on and covers it. Your Mac keeps counting keyboard and mouse idle time as usual.
No. Dimma Screen is a privacy overlay. It keeps coworkers walking past and the person in the next seat off your screen. When you need real security, press ⌃⌘Q. You can also turn on Lock Screen When Keep Awake Ends in Settings. When the time runs out, Dimma Screen hands over to the macOS lock screen. To keep the macOS lock screen on, see how to lock your Mac without turning off the screen.
Type your login password on the panel and press Return. On a Mac with Touch ID, your fingerprint works too.
No. While the screen is on, Dimma Screen holds off display sleep, idle sleep, and the screen saver. Closing the lid or choosing Sleep still puts your Mac to sleep.
Accessibility, so keystrokes go to the PIN panel and not to the app underneath. Screen Recording only if you choose Snapshot.
Yes. All features are free for 3 days. No account or card needed. To keep using it after that, buy it once for $9.90.
Macs with Apple silicon running macOS 26 Tahoe or later.
All features are free for 3 days. No account or card needed. To keep using it after that, buy it once for $9.90. No subscription.
Requires macOS 26 Tahoe or later on a Mac with Apple silicon.