The four things that actually cause this
Most cases of “someone can see what I do on my computer” trace back to one of four setups, not exotic hacking:
- Commercial monitoring software. Products sold for parental control or employee monitoring can end up on an adult’s computer without consent. NNEDV’s Safety Net Project notes it can log every keystroke, website, and chat, and on some products turn on the webcam or microphone, take screenshots, or allow remote control through a web dashboard.
- A remote-access tool, set up once and forgotten. TeamViewer and Chrome Remote Desktop are legitimate tools, but once TeamViewer’s unattended access is set up, a signed-in account “can now connect to it without needing confirmation from the remote side” (TeamViewer Support) — set up during a repair or shared household, it can keep working long after.
- A browser signed into someone else’s view. Sign in to Chrome and it can save bookmarks and passwords to that Google Account, available on any other device signed into it; browsing history and open tabs sync too once the separate “History and tabs” setting is on (Google Chrome Help) — working as designed, for whoever holds the account.
- A keylogger. Software keyloggers run quietly in the background; hardware keyloggers are physical, most often a small device plugged in between the keyboard and the computer, though on a laptop one can be installed inside the case, accessible through a panel (NNEDV Safety Net Project).
If you share devices with the person you’re worried about, read Safety first: before you remove anything before changing or uninstalling anything below. Some people escalate if they realize monitoring software was found and removed, so think through safety and evidence first, and loop in an advocate if you can (NNEDV Safety Net Project).
Check installed programs and browser extensions
Windows: Settings → Apps → Installed apps lists everything on the machine, worth scanning for anything unfamiliar (Microsoft Support). Mac: open Finder → Applications and scan the full list; Apple’s guidance is to find the app there, check for a dedicated uninstaller (which also clears leftover login items), and otherwise drag it to Trash (Apple Support).
Startup items matter too, since monitoring software often hides there to survive a restart: Task Manager’s Startup Apps tab on Windows, or Apple menu → System Settings → General → Login Items & Extensions on a Mac (Apple Support). Browser extensions deserve a separate pass too — in Chrome, the three-dot menu → Extensions → Manage Extensions shows everything installed, with an option to remove anything unfamiliar (Google Chrome Help).
Check who can access your computer remotely, and who’s signed into your browser
Using Chrome Remote Desktop or TeamViewer yourself is normal; the question is whether someone else also has access. For Chrome Remote Desktop, visit remotedesktop.google.com signed into your Google account — any computer set up for remote access appears there, and you can remove anything you didn’t configure. For TeamViewer, check whether it’s installed, and if so, whether unattended access is enabled — the setting that skips the click-to-accept prompt each time (TeamViewer Support). Neither app is a red flag by itself — the concern is a tool you didn’t set up.
Separately, open your browser’s account settings — in Chrome, the profile icon top-right — and confirm the signed-in account is yours alone. A shared or family Google Account, or an old account a former partner still knows the password to, means whatever it’s set to save — bookmarks, passwords, and, if “History and tabs” is on, browsing history — is visible to anyone else signed into it (Google Chrome Help). This is a common, unglamorous explanation for someone “knowing too much” — see Securing your accounts when someone knows you to lock it down without tipping someone off by signing out of everything at once.
Webcam and microphone: what the light can and can’t tell you
Here’s the honest version: the marketing around this runs to overconfidence in both directions.
The webcam LED is a real signal: on a Mac, Apple says the green light glows specifically because the camera turned on (Apple Support). But peer-reviewed research shows it’s weaker than people assume, in two ways. People don’t reliably notice it: Portnoff, Egelman, and colleagues found that only 45 percent of participants doing a task on the computer noticed an illuminated webcam LED, and only 5 percent noticed it when the task was nearby but not on the computer (ACM CHI 2015) — the light isn’t unreliable, attention is. And on some hardware, the light itself can be defeated: Johns Hopkins researchers showed that a class of Apple internal iSight webcams used in some versions of MacBook laptops and iMac desktops could have their firmware reprogrammed to activate the camera while keeping the LED dark, with no special privileges required (iSeeYou, USENIX Security 2014). That flaw applied to specific older hardware, but the lesson holds: an indicator light is a convention, not a guarantee.
Don’t panic over a light you don’t remember seeing — you likely just didn’t notice it — but don’t treat a dark light as proof either. A physical cover removes the question for the camera, though it does nothing for the microphone. Camera access lives at Settings → Privacy & security → Camera on Windows, though some desktop apps can access it even with a setting off (Microsoft Support); on a Mac it’s System Settings → Privacy & Security → Camera (Apple Support).
Turn on your operating system’s own protection — and know its limits
Windows Defender blocks “potentially unwanted applications” by default as of August 2021 — software that degrades performance without counting as outright malware — checkable at Windows Security → App & browser control → Reputation-based protection (Microsoft Support). It’s a reasonable baseline, not a guarantee: monitoring software is often built to look legitimate, or installed by an administrator account, in ways that don’t trip this category. Treat any scan as one data point, not a verdict — What a scan can and can’t tell you covers this: a clean result lowers the odds, it doesn’t rule anything out.
What none of this substitutes for
Checking apps, extensions, remote-access tools, and camera permissions closes the ordinary paths. It won’t catch a hardware keylogger, which needs a physical check, and it can’t prove a negative. If a partner or ex is involved, read What is stalkerware? and Safety first: before you remove anything before removing anything — closing off access can be exactly the moment an abusive person notices and reacts.