AI Overlay for Mercer Mettl Secure Browser on Mac
Mercer | Mettl is the standalone assessment platform Pearson acquired in 2018. It powers a large share of corporate hiring tests and L&D certifications, especially across India, the Middle East, and Southeast Asia, delivered through the Mercer Mettl Secure Browser plus the Mettl Auto Proctor AI layer.
Mercer | Mettl ships two stacked products: the Mercer Mettl Secure Browser, a Chromium-based lockdown wrapper that disables tab switching, copy/paste, screen-sharing tools, external ports, and printing; and the Mettl Auto Proctor, an AI layer that adds webcam-based facial recognition, audio analysis, and continuous window-violation detection. Neither product runs at kernel level on macOS; the Secure Browser is a notarized user-space Chromium fork, and Auto Proctor is a WebRTC pipeline that captures via getDisplayMedia. Both surfaces are bound by the same compositor rule: macOS will not include a window in screen-capture output if that window has been flagged with kCGSWindowSharingNone. LDBypass sets that flag at window creation, so even when the Secure Browser kills Cmd-Tab and the Auto Proctor live-streams to a reviewer, the overlay window is simply not in the frames either of them get.
Key points
- Mercer | Mettl was founded in 2010, acquired by Pearson in 2018, and continues to ship under the dual-branded Mercer | Mettl name.
- The Secure Browser is a Chromium fork; it can block external monitors, USB drives, and remote-desktop tools, but cannot see windows the OS has marked private.
- Auto Proctor adds 3-point facial authentication and continuous webcam monitoring; the webcam pipeline is separate from screen capture and behaves normally.
- Mettl flags "window violations" (focus loss). LDBypass overlay is a separate macOS window that never grabs focus from the exam tab, so no focus-loss event is generated.
- Common Mettl integrations include D2L Brightspace and direct SaaS delivery; both share the same secure-browser capture path on Mac.
How it works
┌── macOS host ─────────────────────────────────┐ │ ┌── Safari/Chrome ─────────────┐ │ │ │ ┌── proctoring extension ─┐ │ │ │ │ │ Browser screen-capture │ │ ← reads │ │ │ │ → exam recording │ │ visible │ │ │ └─────────────────────────┘ │ pixels │ │ └──────────────────────────────┘ │ │ │ │ ┌── LDBypass overlay ──────────┐ ← rendered │ │ │ ChatGPT / Claude / Ollama │ excluded │ │ └──────────────────────────────┘ from cap │ └───────────────────────────────────────────────┘
Compatibility on Mac
| macOS 14 Sonoma+ | Yes (required for window-privacy API) | ✓ |
| Apple Silicon (M1/M2/M3/M4) | Native arm64 build | ✓ |
| Intel Macs (2019+) | Universal binary supported | ✓ |
| Mercer Mettl Secure Browser (Mac) | Chromium fork, user-space only | ✓ |
| Mettl Auto Proctor (WebRTC) | getDisplayMedia respects window privacy | ✓ |
| Mettl USB / external-port lockdown | Unrelated to overlay; both coexist | ✓ |
Common questions
Does the Mettl Secure Browser block LDBypass from launching?
No. Mettl lockdown blocks tab-switching, copy/paste, and screen-sharing apps it can name. LDBypass uses a randomized innocuous bundle ID per build and never tries to share screen content.
Will Auto Proctor window-violation detector flag the overlay?
No. The detector listens for focus loss in the browser tab. LDBypass overlay does not take focus when toggled, so the Mettl tab keeps focus.
Does Mettl detect virtual machines on Mac?
Mettl checks for VMs through browser fingerprinting and timing heuristics. LDBypass runs on bare-metal macOS and does not introduce any VM signal.
I am taking a Mettl hiring assessment. Is using AI a policy violation?
Yes, almost certainly. Mettl is used for high-stakes hiring decisions and AI assistance is treated as fraud by virtually every employer that runs Mettl tests.
Does the overlay work if my employer runs Mettl through D2L Brightspace?
Yes. The Brightspace integration is just an LTI handoff; the actual exam delivery still runs through Mettl Secure Browser or Auto Proctor on Mac.