A solid red screen in fullscreen. Use it as a dim red night light, a red accent light for photos and video, or to check your display for stuck pixels.
How to use the red screen
- Press F or the fullscreen button.
- Lower the brightness for a night light, or turn it up for accent light.
- Move the mouse or tap to bring the controls back. Press Esc to leave fullscreen.
Ways to use a red screen
- Night light
- Dim red light is easy on eyes that have adjusted to the dark, which is why astronomers and pilots use it.
- Accent light for video
- Place the screen to one side and behind you for a red rim light on your hair and shoulders.
- Stuck pixel test
- A sub-pixel that is stuck off shows as a dark dot on red. Check the green and blue screens too.
- Signals and parties
- Use a phone as a red light for a game, a stop signal or a party.
Questions
Is red light better at night?
Dim red light disturbs dark-adapted vision less than white or blue light, so it is a common choice for night lights. Keep the brightness low.
Can a red screen replace a darkroom safelight?
Not reliably. A screen's red is not a pure narrow band, and some photo papers react to it. Test with a strip of paper first.
How do I go fullscreen?
Press F on a keyboard, or use the fullscreen button in the bar at the bottom. Press Esc or F again to leave. On iPhone, Safari does not allow real fullscreen, so add the page to your home screen for the cleanest view.
Is it free?
Yes. There is no account, no download and no time limit. It runs in your browser and never asks for camera, microphone or location access.