Does Zoom Detect Overlay Apps? What Zoom Can and Can't See

"Detect" can mean four different things

People typing this question into Google usually mean one of these. They have different answers, so it helps to split them up.

1. Does Zoom tell anyone? Will the host or another participant get an alert or a list of your apps? No.
2. Does the overlay appear in my share? It depends on the share mode and the overlay. This is the one that matters most, and most of this page is about it.
3. Can the Zoom app on my PC see other windows? Technically any desktop app can ask Windows which windows exist. Zoom doesn't document doing anything with that for meetings.
4. Does a recording catch more than the live share? No. A Zoom recording contains what was shared, not your whole desktop.

What Zoom shows in each share mode

On Windows, Zoom's share dialog has a Screens tab (whole screen or specific app windows), a Documents tab (whiteboard, Zoom Docs, cloud files) and an Advanced tab with a portion of screen, computer audio, video files and a second camera (Zoom Support: sharing your screen). Here's how a typical always-on-top overlay behaves in each, compared with one that's excluded from capture.

That last row is the honest one. A camera, whether it's a document camera, a webcam or a phone, films the physical screen. No software setting changes what light comes out of your monitor.

Portion of screen is not a privacy feature

"Portion of screen" shares whatever sits inside a green rectangle you can drag and resize. People sometimes park notes just outside the rectangle and feel safe. That's fine until you move the notes window, or a dialog opens in the middle of the screen, or the overlay snaps to a position inside the frame after a resolution change. It's a framing tool. Treat it like one.

What the host controls, and what it doesn't

Hosts get real power over sharing, just not over your desktop. They can limit sharing to the host only, allow one participant or several to share at a time, and decide who can start sharing while someone else is presenting. They can't view your screen unless you share it, and remote control is something you grant: a participant can request it, and nothing happens until you approve. If a host asks you to share your entire screen, that's a request you can answer with "I'll share the window instead". In most business meetings nobody minds, and it's the cleaner option anyway because notifications stay out of it.

Zoom already hides its own windows

Here's a detail most guides skip. Zoom's help center says Zoom's own window isn't shared by default when you share your screen. There's an option in Zoom's share settings to show Zoom windows during screen share for when someone is helping you use Zoom and needs to see its controls. So the idea of "a window that's on your screen but not in the share" isn't exotic. Zoom applies it to its own meeting controls every time you present.

The attention-tracking feature that no longer exists

A lot of the worry around this topic comes from 2020. Zoom used to have an "attendee attention tracking" option that alerted the host when a participant didn't have the Zoom window in focus for more than 30 seconds while someone was sharing. The Electronic Frontier Foundation called it out in a privacy report, and Zoom removed it permanently as part of the security and privacy changes CEO Eric Yuan announced on April 1, 2020 (Zoom blog). There's no current Zoom feature that tells the host you clicked into another app.

The 2021 bug that leaked overlapping windows

If you've read that Zoom "can see overlays", this is probably the source, and it's a real one. Researchers Michael Strametz and Matthias Deeg at SySS found that when a presenter shared a single application window, Zoom could briefly transmit the contents of other windows placed on top of it, for a few frames, when those windows got focus. A participant recording the meeting could step through the video and read them. It was assigned CVE-2021-28133 (CVSS 4.3), affected Zoom on Windows and Linux through version 5.5.4, and was reported to Zoom in December 2020.

Two lessons from it. First, keep Zoom updated, because sharing code is complicated and bugs like this get fixed in later releases. Second, "share a window" is safer than "share a screen" but it isn't a vault. If a window holds something that would hurt to leak, close it before the call.

Can the Zoom app on your PC see other windows?

Any Windows desktop program can list top-level windows, read their titles and even query whether a window is excluded from capture; IOActive's 2026 write-up on the flag notes that any process can call GetWindowDisplayAffinity (IOActive). That's how Zoom's share picker can show thumbnails of your open apps in the first place. What Zoom doesn't do, as far as its documentation shows, is send that list to the meeting.

If you're on a company laptop, think beyond Zoom. Employers may run endpoint monitoring or data loss prevention software with far more visibility than a meeting app. Follow your organization's policy, and don't use any tool in a way your employer or meeting host has ruled out.

How capture-excluded overlays work with Zoom

Windows 10 version 2004 added a window setting, WDA_EXCLUDEFROMCAPTURE, that Microsoft describes as a window "displayed only on a monitor. Everywhere else, the window does not appear at all" (Microsoft Learn). The Desktop Window Manager draws the window for your display and leaves it out of the frames given to capture tools. Zoom's screen share reads those frames, so the overlay simply isn't in them. Viewers see the app underneath.

AuraCloak, an invisible AI overlay for Windows, sets that flag on its own window. Zoom, Teams, Google Meet in a browser, OBS and the Snipping Tool leave it out. It's handy on sales calls where you share a demo and want pricing answers or objection notes at hand; the sales calls use case shows that setup. You can also run ChatGPT or Claude inside it with browser mode.

The limits are the same ones Microsoft lists: the flag "is not a security feature". It doesn't hide the window from a phone camera, a projector, a duplicated display or a capture card on your video output. On Windows builds before 2004, AuraCloak falls back to the older setting, so viewers see a black rectangle where the overlay is.

Test it yourself in five minutes

1. Start a Zoom meeting on your PC.
2. Join the same meeting from your phone, with the phone muted and its speaker off to avoid echo.
3. On the PC, open the overlay or notes window you care about.
4. Share Screen and look at the phone. Then try a window share and a portion share.
5. Open a notification (send yourself a chat message) to see what slips through.
6. Stop sharing. If anything showed that shouldn't, fix it now, not during the client call.

A longer version that covers Teams, Meet and OBS is on our screen share visibility test page.

FAQ

Can Zoom see other tabs when I share my screen?

Only the tabs visible in what you share. If you share your whole screen and switch tabs, viewers see each tab. If you share a different app window, your browser tabs aren't sent. Zoom does not list your tabs to anyone.

Does Zoom notify the host if I switch to another window?

No. Zoom removed its attendee attention tracking feature in April 2020, and there's no current feature that alerts the host when you click into another app.

Can Zoom see my screen when I'm not sharing?

No. Without an active screen share, Zoom sends your camera video and microphone audio only. Other participants can't view your screen unless you start sharing it.

Does sharing a portion of the screen hide my overlay?

Only if the overlay stays outside the green border. Anything that moves into the shared rectangle becomes visible, so it's a framing tool rather than a reliable way to keep a window private.

Will my overlay show up in a Zoom recording?

A Zoom recording contains what was shared. If the overlay was visible in the live share, it's in the recording; if it was outside the share or excluded from capture, it isn't.