**TL;DR** — Respondus LockDown Browser (LDB) is a locked-down Chromium build. It prevents tab switching, screenshots, screen recording, virtual machines, and remote-desktop tools while an exam is active. Paired with Respondus Monitor, it also records your webcam.
Last updated: July 2026.
What LockDown Browser blocks
- Alt-tabbing or switching to another application.
- Screenshots (PrtScn, macOS shortcuts, Snipping Tool).
- Screen-sharing apps (Zoom, Discord, Teams).
- Virtual machines (VMware, VirtualBox, Parallels).
- Screen recorders (OBS, Camtasia, macOS QuickTime).
- Right-click, copy/paste, and print-to-PDF inside the exam.
What it does NOT do without Respondus Monitor
Base LDB does not record your webcam or microphone. It's only browser sandboxing. Add-on Respondus Monitor is what turns it into a proctored exam.
How LMS integration works
LDB uses a browser-lock token that Canvas / Blackboard / D2L / Moodle issues at exam-start. Without a valid token from your school's LMS, exams cannot be opened.
Known bypass attempts (and why they don't work)
- Second monitor — LDB detects and blocks it. Exam won't start.
- VM — LDB checks for hypervisor signatures and refuses to launch.
- Remote desktop — same detection layer.
Legitimate troubleshooting
- Camera won't initialize: check macOS Screen Recording permissions.
- Exam won't start: uninstall other browsers' PDF viewers that hook the same APIs.
- Wi-Fi drops mid-exam: LDB auto-reconnects; your answers save every 60 seconds.
If you need genuine exam preparation instead of workarounds, see our [online exam help service](/services/online-exam-help).
**Sources**: Respondus Technical Documentation (2026), Instructure LDB Integration Guide (2026).