Do Zoom, Teams and Google Meet Detect Screen Overlays?

If you're preparing for a video-call interview and researching whether an on-screen overlay — notes, a teleprompter, an assistant window — would show up in your share, the honest answer requires understanding how these apps actually capture your screen. It's not magic on either side. Here's what's really happening.

How Zoom, Teams and Meet capture your screen

None of the major video-conferencing apps read pixels directly off your monitor's cable. On Windows, they all go through the operating system's compositor — the same system component (DWM, the Desktop Window Manager) that's responsible for drawing every window you see. When you click "Share Screen," the app asks Windows for a capture surface, typically via the Desktop Duplication API or the newer Windows Graphics Capture API, and Windows hands back a live feed of the composited desktop.

This matters because it means the video-conferencing app is a consumer of whatever Windows decides to include in that feed — not an independent observer with its own line of sight to your screen. If Windows excludes something from that feed, Zoom, Teams and Meet never see it in the first place. They're not failing to detect it; there's nothing in the data stream to detect.

The mechanism: window-level capture exclusion

Since the Windows 10 May 2020 Update, applications can mark one of their own windows with a display-affinity flag called WDA_EXCLUDEFROMCAPTURE. Once set, DWM stops including that window in any capture surface — while still rendering it normally on the physical display. We've written a full technical breakdown of how this API works if you want the details, but the short version is: it's a documented, one-line Windows API call, not a hack against Zoom or Teams specifically.

This is the important distinction. A window using this flag isn't evading Zoom's detection — Zoom was never built to look for it, because there's nothing to look for. The screen-sharing pipeline is capturing a composited frame that, by design, doesn't include the excluded window's pixels. Zoom's screen-share code doesn't run any "look for hidden windows" logic, because that's not how screen capture works on Windows — it consumes whatever the OS compositor gives it.

Could a meeting app add detection for this?

In principle, a video-conferencing client running locally on your machine could enumerate all open windows via EnumWindows and cross-reference that list against what's actually appearing in its own capture feed, flagging any visible-but-not-captured window as suspicious. This is architecturally possible. As of this writing, none of Zoom, Microsoft Teams, or Google Meet publish or are known to implement this kind of active countermeasure — their screen-share features are built for sharing your work, not auditing your desktop for excluded windows.

Dedicated proctoring and assessment platforms are a different story, and worth treating separately — see our post on how interview cheating detection actually works for what tools built specifically for exam integrity tend to check.

What screen-share capture exclusion doesn't hide

It's worth being precise here, because it's easy to over-claim. Window-level capture exclusion is specific to what appears in the shared video frame. It has no bearing on:

• Audio. If your microphone picks up something, it's transmitted regardless of any window flag.
• The taskbar and Alt-Tab. Those require separate window properties to suppress, and are visible to you, not to remote participants, unless you share your entire screen including the taskbar in a way that would show a labeled entry.
• Physical recording. A phone camera pointed at your monitor sees whatever the monitor is displaying — window-capture exclusion is a software layer between your GPU and network, and has no effect on light bouncing off a physical screen.
• What you say and do. No technical mechanism changes how an interview actually goes; it just determines what's visible in a screen-share frame.

The practical upshot

If your question is specifically "will my screen-share software surface this window to the other person," the answer is grounded in a real, well-documented Windows capability, not folklore: a window can genuinely be excluded from Zoom, Teams, Meet, Webex, and OBS captures via SetWindowDisplayAffinity, because all of them read from the same OS-level capture surface that respects the flag.

Where you should stay skeptical is any claim that goes beyond that — "100% undetectable by everything," "hides your process," "works on every platform including proctored exams." Those are different claims requiring different mechanisms, and some of them (hiding a running process from Task Manager, for instance) aren't things this API does at all.

Related reading

• How Windows screen capture exclusion actually works — the technical deep-dive
• How interview cheating detection works — proctoring and assessment platforms, which are architecturally different from video calls
• Can HackerRank detect cheating? — a platform-specific breakdown