Peeker vs 3M Privacy Filter: Software Detection vs Hardware Filter

If you've ever searched for a way to stop people from reading over your shoulder, you've probably landed on two very different answers. One involves sticking a plastic film on your laptop. The other watches the room for you. 3M has owned the hardware category for decades. Peeker is a newer software approach. They solve the same problem in almost opposite ways, which makes a direct comparison genuinely useful instead of marketing fluff.

This post is the long version. The short version is below.

Quick verdict

3M is the right call if you want a permanent, always-on barrier and don't mind a dimmer screen, $30 to $90 per device, and a slightly muddy viewing experience. Peeker is the right call if you work on a Mac, want one $5/year subscription that follows you between machines, and don't want your screen to look like it's been dipped in coffee. They can also be combined, and many people do exactly that.

What 3M actually is

3M's privacy filters are physical sheets, usually polarized louvre film, that you either slide into a frame, attach with adhesive tabs, or magnetically snap onto your screen. The louvres act like microscopic blinds. Look at the screen straight on and you see everything. Move 30 degrees off-axis and the content goes black or grey.

3M invented the original technology in the 1980s and still makes the premium versions. A 13-inch MacBook filter usually runs around $40 to $60. A 27-inch monitor filter can hit $90. They're sold by 3M directly and through Amazon, Staples, and corporate IT resellers. The brand is the default in finance, law, healthcare, and government procurement.

What Peeker actually is

Peeker is a macOS app that uses your existing webcam to detect when another person is behind you. When it sees someone, it shows a small live preview of what's behind you in the corner of your screen. You glance, you see them, you decide what to do. The camera feed never leaves your machine.

Peeker is $5/year. One subscription covers your Macs. It runs in the background, uses around 2 to 4% CPU, and starts the moment you log in. It was built specifically for the post-2020 reality of open offices, cafes, coworking spaces, and airline tray tables.

Head-to-head

Protection model

3M is preventive. Even if someone is reading over your shoulder right now, they can't see your screen. You don't need to know they're there. Peeker is reactive. It tells you someone is behind you so you can choose what to do, whether that's locking the screen, switching tabs, or angling your body. Different mental models for the same problem.

Cost over time

A 3M filter for a 14-inch MacBook Pro is about $50. If you also use a 27-inch external monitor, that's another $80. New laptop next year? Another $50. Peeker is $5/year, regardless of how many Macs you own or how often you upgrade. Over five years and two devices, you're looking at roughly $260 for 3M versus about $25 for Peeker.

Screen quality

This is where 3M loses people who actually look at their screens for a living. A privacy filter cuts brightness noticeably and adds a faint warm tint. For spreadsheets and email, it's fine. For design work, video editing, or anything color-critical, it's a daily annoyance. Peeker is invisible to your screen.

Scenarios

3M wins on planes. The seat behind you is fixed, the person next to you has a guaranteed angle, and you cannot reposition. A filter solves that perfectly. Peeker wins in offices and cafes, where threats move around and you want to keep your screen looking normal during client meetings.

Where each one wins

3M is the right answer when you're stationary in a high-traffic, fixed-geometry environment. Open-plan offices where the same coworker sits behind you every day. Airline seats. Trading floors. Anywhere a permanent physical barrier is genuinely better than situational awareness.

Peeker is the right answer when threats are unpredictable and you don't want to compromise screen quality. Cafes. Coworking spaces. Hotel lobbies. Trains. Anywhere you might use your laptop for an hour and then move on. Also worth considering if you've tried a 3M filter and hated the dimming, which is the most common complaint in reviews.

Hardware filters and software detection aren't really competitors. They're different tools that happen to solve adjacent problems.

For more on this, see our post on the best privacy screen filter alternatives in 2026 and our comparison of webcam-based privacy apps for Mac.

The verdict

If you mostly work in one fixed location with people consistently behind you and you don't mind a dimmer screen, get a 3M filter. If you move around, work on a Mac, care about color accuracy, or just want to spend $5/year and be done with it, get Peeker. If you're paranoid and have the budget, run both. The combination gives you a physical barrier plus an alert when someone gets close.

Try Peeker for $5/year

If the software-detection approach makes sense for how you work, Peeker is a $5/year subscription at getpeeker.com, with a 7-day free trial and no card required to start. Works on any Mac running macOS 13 or later. No account, no data leaves your machine.