Frequently Asked Questions

Night Shift only goes so warm — it caps at around 2500K, which is roughly the warmth of an old tungsten bulb. Tap Zap can take you all the way down to a fully red screen, which is the only way to actually eliminate blue light rather than just reduce it. Night Shift also doesn't touch your backlight, so even at maximum warmth you're still getting the same flicker if your screen uses PWM dimming.

The Color Filters in System Settings → Accessibility are designed for color blindness, not for sleep. They apply a fixed red, green, or blue tint that you can't fine-tune, they don't get warm enough to actually block blue light, and they don't do anything about your backlight or PWM. Useful if you're colorblind. Not useful if you're trying to wind down at night.

Night Light has the same limit as Apple's Night Shift — it warms your screen by reducing blue, but it stops short of eliminating it. It also leaves your backlight alone, so PWM flicker continues regardless of how warm you make the screen. Tap Zap goes deeper on warmth and adds the flicker control on top.

f.lux is a solid app and we have a lot of respect for what it pioneered. That said, its warmth bottoms out around 1900K and stops there, and it doesn't touch your hardware brightness, so it doesn't address PWM flicker at all. Tap Zap goes further on warmth and pins your backlight at 100% to stop the flicker entirely.

Iris is powerful, but it's also a lot of app — dozens of menus, schedules, modes, and settings to wade through before you find what you came for. Tap Zap is deliberately stripped down: two sliders, three presets, and one ZAP button. It also pins your backlight at 100% to stop PWM flicker, which is the part most flicker-sensitive users actually need and Iris doesn't offer.

Best to pick one. All of these tools are reaching for the same display controls, and stacking them on top of each other tends to produce unpredictable colors and double-warming. Turn off Night Shift, Night Light, or any other warming filter before using Tap Zap and you'll get cleaner results.

That's the goal, not a bug. To actually eliminate blue light — not just reduce it — the screen has to stop emitting the wavelengths blue light comes from. What's left is the long-wavelength red end of the spectrum, which research links to the lowest melatonin suppression. If pure red feels like too much, just slide the warmth back up; anywhere from amber to neutral works.

You're right, it's a naming convention rather than a real color temperature. 6500K on the slider is neutral daylight. As you slide down toward 0K, the screen progressively loses blue and then green, until at 0K it's emitting only red. Think of it as the floor of the warmth range rather than a physics reading.

Yes. Long-wavelength red is the least energetic part of the visible spectrum — there's nothing harmful about it. Plenty of people use red lighting in the evening for this exact reason. The bigger eye-strain trigger for most people is high blue exposure and PWM flicker, both of which Tap Zap is designed to remove.

Most LED-backlit screens dim themselves by switching the backlight on and off thousands of times per second. It's called pulse-width modulation, or PWM. Your conscious eye can't see the flicker, but your visual system can still track it, which is where a lot of unexplained eye strain, headaches, and "this screen feels off" sensations come from. People who are sensitive to it usually feel the difference within minutes.

It's a toggle inside Tap Zap that pins your backlight at 100% so it stops flickering, then dims your screen in software instead. Your warmth and brightness sliders still work the way you'd expect; the hardware just never enters PWM territory. On Mac it works on built-in laptop panels, the Studio Display, and the Pro Display XDR. On Windows it works on built-in laptop panels and most external monitors with DDC/CI support.

Slightly. Your backlight is running at full power even when the screen looks dim, which costs a bit more energy than PWM-based dimming. That said, most flicker-sensitive users were already keeping their hardware brightness at 100% manually to avoid PWM, so for them there's no real change. The toggle is opt-in either way.

On Mac, the underlying API only talks to Apple-controlled displays — most third-party HDMI/DisplayPort monitors don't expose this kind of control. On Windows, Tap Zap reaches external monitors through DDC/CI, which most modern displays support but some budget panels don't. If your external doesn't show up as controllable, the toggle hides itself and the standard brightness reminder appears instead.

Yes. Tap Zap automatically detects every connected display and applies the warmth filter to all of them. Plug in a new monitor mid-session and it picks up the filter instantly — no restart, no reconfigure. On Windows, the same is true, and any external that exposes DDC/CI also gets the PWM-Safe backlight lock.

Not yet. Tap Zap is intentionally manual right now — you set it when you want, and turn it off when you don't. Auto-scheduling is on the roadmap, though a lot of users actually prefer the manual approach because it lets them decide whether a given evening is a screen-off, screen-warm, or screen-normal kind of night.

macOS 12 (Monterey) and later, on both Apple Silicon and Intel Macs, plus Windows 10 and later. There's no iOS, Android, or Linux version — the system-level color and backlight control Tap Zap relies on simply doesn't exist on those platforms.

Yes, on all of them. The macOS app ships as a universal binary, so it runs natively on every Apple Silicon chip and on Intel Macs that are still on macOS 12 or later.

Sandboxed App Store apps can't touch the system gamma tables or the private display APIs that Tap Zap needs to do its job. Same reason f.lux isn't there. Distributing outside the App Store also lets us push updates the day they're ready, without going through review.

No, and there isn't a clear path to one. Mobile operating systems lock down the color and brightness controls Tap Zap relies on. iOS has its own Night Shift built in, and that's about as far as you can go without a jailbreak. If that ever changes, we'll be the first to ship it.

No on both platforms. On Mac, the filter is applied as a final display overlay, so screenshots, screen recordings, and anything you share on Zoom or Google Meet look completely normal to everyone else. On Windows, the same is true — screenshots come out clean, and most screen-share and recording tools capture the un-tinted frame because Tap Zap's color effect is applied at the display compositor level. If you ever want to be absolutely sure before sharing, hit the OFF preset and the screen reverts instantly.

Hit the OFF preset, or click the ZAP button to toggle the filter off. The screen reverts to its true colors instantly — no delay, no logout, no restart. When you're done, click again and you're back where you were. A lot of photographers and editors run Tap Zap during regular hours and just toggle it off when they sit down to grade.

Yes on both platforms. The filter sits at the display layer, so it covers fullscreen games, HDR video, browser tabs, terminals, and everything in between. There's no per-app exclusion list to maintain, and nothing slips out from under it.

Three. One purchase covers your laptop, your desktop, and one more machine if you have it. You can deactivate a device from inside the app at any time to free up a slot, so swapping computers down the line isn't a problem.

Not at the moment. What we offer instead is a 30-day no-questions-asked refund — buy it, use it for a few weeks, and if it's not for you we'll send your money back. We'd rather you actually try the app on your own setup than poke at a hobbled trial version.

Email support from the address you bought with and we'll resend it. Your original purchase email from DodoPayments also has the key in it, so check that inbox first if you still have it.

Because a blue light filter shouldn't be a recurring charge. You buy Tap Zap once, you get every future update for free, and that's the end of it. No account, no auto-renew, nothing to cancel later when you forget you signed up.

Almost none. Roughly every 90 days the app checks in with the license server to confirm your key is still valid — that request contains your license key and a device ID, and nothing else. No analytics, no telemetry, no account, no email tracking, no ads. The app works completely offline most of the time.