How Invisible Notes Actually Work on macOS (the Technical Explainer)
Published 2026-10-01 · 6 min read
Invisible notes on a Mac come from one window property: NSWindow.sharingType, set to the value that gives other processes no access to that window's content. Zoom, Loom, and OBS ask macOS for screen pixels; the flagged window isn't in what they receive. Your physical display still shows everything, so you read normally while the capture doesn't.
That's the answer. The rest is the interesting part: where the property comes from, why the capture app has no say in the matter, the one Zoom setting worth knowing, and what no window flag can ever hide. I created GlideRail, an app built on exactly this mechanism, so weigh the product mentions accordingly. If you'd rather start with the plain-English category overview, that's what is an invisible teleprompter.
What makes a Mac window invisible to screen capture?
A Mac window becomes invisible to screen capture through one AppKit property: NSWindow.sharingType. Every window on a Mac is backed by an object called NSWindow, and Apple's documentation describes sharingType as controlling the level of access other processes get to that window's content. An invisible notes app sets it to the no-access value on every window it creates. The property has shipped with macOS since 10.5 Leopard (2007): a first-party switch older than the App Store, not an exploit.
The values come from an enum, and the interesting one is .none: it means no other process can read this window's contents at all. GlideRail, a conversation rail for your Mac, sets that value on every window it creates: the main notes windows, the sticky notes, the floating clipboard. A single visible straggler would defeat the whole point.
That's the entire trick. One property, set at window creation. Everything else in this post is about what happens downstream.
Why can't Zoom, Loom, or OBS see the window?
Zoom never decides to hide invisible notes, because Zoom never sees them. Capture apps on macOS (Zoom, Loom, OBS, QuickTime) don't crawl your windows themselves; they ask macOS for screen content, macOS composites the frames, and a window flagged as non-shareable isn't in the frames it hands over. The exclusion happens inside the operating system, upstream of every capture app.
Specifically, when you click share in Zoom, or record in Loom, or capture in OBS, the request goes through Apple's capture pipelines: the older CoreGraphics path, or ScreenCaptureKit, the modern framework for streaming screen content to an app. The capture app receives a desktop where your notes never existed, with whatever was behind the window showing through.
Three things follow from that. Nothing installs into the call software: no Zoom plugin, no virtual camera, no browser extension. The app flags its own windows and macOS does the rest.
It also works the same everywhere, because Zoom, Meet in a browser, Teams, Loom, OBS, and QuickTime are all downstream of the same system pipelines. A browser sharing a screen is just another process asking macOS for pixels.
And there's nothing to "reveal." The viewer's side has no toggle, no blur to remove, no hidden layer in the recording file. The pixels were never transmitted or written.
For the Zoom-specific version of this question (including what the other side sees during a full-desktop share), see can Zoom see your other windows?
Which apps can't see GlideRail?
GlideRail's invisible windows never appear in Zoom, Google Meet, Microsoft Teams, Loom, OBS, or QuickTime captures, live shares and recordings alike, on macOS 14 and later. Zoom needs one setting: its screen capture mode set to "Advanced capture with window filtering" (Settings, Share Screen, Advanced), because Zoom's default "Auto" mode can include them on some Macs. Here's the full list:
| Capture surface | Sees your notes? |
|---|---|
| Zoom: live share and recordings (Advanced capture with window filtering) | No |
| Google Meet: live share | No |
| Microsoft Teams: live share and recordings | No |
| Loom recordings | No |
| OBS capture | No |
| QuickTime / Shift-⌘-5 screen recordings | No |
| Your own physical display | Yes, that's the point |
| A phone camera aimed at your screen | Yes, always |
| A person standing behind you | Yes |
One honest asterisk on the table: in GlideRail, invisibility is a Pro feature. Free-tier windows are deliberately visible and labeled "Visible" in the app, so there's no ambiguity about which state you're in. For how this plays out in a real recording workflow, see notes invisible to screen recording.
What no flag can ever hide
No window flag hides what's physically on a screen. A phone camera pointed at your display sees your notes, people in the room see them, and your own eyes stay on camera even when the notes don't. The sharingType mechanism removes windows from capture streams, not from the glass. Worth saying twice.
A physical camera sees everything. A phone pointed at your display, a photo of your panel, a colleague's camera catching your monitor in the background: the notes are right there, because they really are on your screen. Light doesn't care about window properties. And people in the room see your screen too (obviously), which makes invisible notes a video-call tool, not a general-purpose privacy shield.
Your eyes are the third thing. The capture never shows your notes; it always shows you. Eyes tracking line by line across a distant monitor read as reading. That's a placement problem (put the notes window near your webcam), not something any flag solves.
FAQ
Does this need a virtual camera or a Zoom plugin?
No. The app sets a property on its own windows; macOS excludes them when building capture frames. Nothing runs inside the call software, which is also why the behavior is identical across Zoom, Meet, Teams, Loom, OBS, and QuickTime: they all drink from the same system pipelines.
Do invisible notes work in browser-based calls like Google Meet?
Yes. When Chrome shares your screen, it's just another process requesting pixels from macOS, so the exclusion applies the same way. Google Meet live shares leave GlideRail's windows out. The same logic covers other browser-based tools that share a screen or window from a Mac.
Does invisibility keep working after macOS updates?
Yes. GlideRail supports macOS 14 and later, and its updates arrive inside the app, so its windows stay out of Zoom, Meet, Teams, Loom, OBS and QuickTime. On Zoom, keep the screen capture mode on "Advanced capture with window filtering".
Are invisible windows missing from screenshots too?
Yes. Take a screenshot with Shift-⌘-3 while a GlideRail note is invisible: the note is on your screen and absent from the image. GlideRail's own setup uses exactly that to show you invisibility working.
Do you need Apple Silicon for invisible notes?
No. Invisibility works on any Mac running macOS 14 or later, Intel included. In GlideRail, only the voice features (Live Rail and Voice Follow) require Apple Silicon; invisibility, click-through, and Cue Mode's manual navigation don't care what chip you have.
Why can you see the notes if the capture can't?
Your display shows the full composited desktop: every window, flagged or not, because you're looking at the physical panel. The capture stream is assembled separately for the process that requested it, and the flagged window is left out of that. Two consumers, two different frames.
The quickest way to see it is on your own Mac. Download GlideRail free: the free version stays free, and the 7-day free Pro trial covers invisibility. Flip it on, hit Shift-⌘-5, record ten seconds, and open the file. Your notes won't be in it.
Written by Takumi, maker of GlideRail. Last updated October 6, 2026.