I built this because working late kept giving me headaches that carried into the next day. I use OLED monitors, which look incredible but I've found that they make it worse. I discovered that switching to a real red light at night actually helped. I ended up trying several apps but they all just throw a red tint over your screen, which doesn't really do much. I wanted the real thing.
Cindershift shifts the color and brightness of your screen through the day so your eyes aren't getting hit with blue light late at night. You pick how warm and how dim you want it at different points in the day, and it handles the rest in the background. When you really need it, one key drops your whole screen into a true red light mode. Not a filter sitting on top, the actual light coming off the display.
It stays out of your way. Small, quiet, and you can bind everything to whatever keys you want.
The same desktop with the effect off, then pure red, monochrome red, and amber. This is a phone photo of the screen, not a screenshot - Cindershift changes the actual light coming off the panel, so a screen capture never shows it. That is the whole point: real red light, not a tint layered on top.
- Shifts warmth and brightness automatically through the day, either on a built-in schedule or anchored to your local sunrise and sunset
- A true red light mode you trigger whenever you need it, not a red tint layered over the screen
- Brightness you can drop lower than your monitor normally allows, which also helps with the flicker some screens get at low brightness
- Bind any action to any key combo or mouse side button you want
- Lives in the tray and stays quiet until you want it
This is the part I cared about most. A red tint drawn on top of your screen doesn't do much, because the screen is still pushing out all the blue and green light behind it. Cindershift changes the actual signal going to your display so the green and blue basically stop, and what is left is real red light. On an OLED those pixels put out nothing extra, so the red comes through clean. Blue light late at night is the thing that messes with your sleep, and for me my head, so cutting it is the whole point.
There are three red modes and you cycle through them with a key:
- Monochrome red turns everything into shades of red so you can still read and use your screen normally.
- Pure red drops green and blue completely, which is the simplest and most solid version. This is my personal favorite; it is my love child and you can't take him from me.
- Amber is monochrome's softer cousin. Same readable idea, but it lands on a warm amber glow instead of a hard red, which is gentler on the eyes.
Cindershift is a local app. It does not phone home, has no telemetry, and makes no network calls on its own. There is exactly one thing that can go online, and only when you ask for it: looking up your location for the Day cycle.
You set your location in Settings, and you choose how. Type your latitude and longitude and it stays fully offline, worked out on your own machine. Or type a postal code or place name and press Set, and it sends just that text to OpenStreetMap to find the coordinates. The screen tells you that before you press it, and it only happens on that press. You can also skip location entirely and Day cycle falls back to fixed clock times. Whatever you pick, nothing about you is tracked and nothing is stored anywhere but your own config file.
Cindershift dims in software instead of leaning on your monitor's own brightness. That matters for two reasons. It works the same on every display, including external monitors that ignore brightness controls, and it can go darker than the hardware usually lets you. It also keeps a lot of screens out of the low brightness range where they start to flicker, which is a known cause of eye strain and headaches.
Windows is ready to use. The daily warmth and brightness cycle, all three red modes, the red cursor, the tray icon, the settings window, and location scheduling are all working. macOS and Linux are experimental and unverified. Some backend code exists, but Cindershift has never actually run on a Mac or a Linux box, so for now this is Windows only and Windows is the only platform I stand behind. Downloads show up on the releases page.
Grab cindershift.exe from the latest release and run it. A setup window appears asking where you want shortcuts — desktop, Start Menu, taskbar, and whether to start with Windows. Pick what you want, click Install, and it is running.
After that it lives quietly in the tray and starts with Windows. Clicking the desktop or Start Menu icon opens Settings (it does not launch a second copy); if it was closed, clicking starts it again.
One note on the taskbar: Windows 11 does not let an app pin itself there, so if you want a taskbar button, right-click the desktop shortcut and choose "Pin to taskbar." The desktop and Start Menu shortcuts always work.
To quit, open Settings and click Quit, or right-click the tray icon and choose Quit Cindershift (Ctrl+Alt+Q also works). Any of these restores your screen. To stop it starting with Windows, run cindershift autostart off from a terminal.
- Ctrl+Alt+R cycles the red modes: off, monochrome, pure, amber
- Ctrl+Alt+Up and Ctrl+Alt+Down make the screen brighter or dimmer
- Ctrl+Alt+Q quits and puts your screen back to normal
Right-click the tray icon (or double-click it) for Settings. In there you choose Day cycle, where the screen shifts through the day on its own, or Constant, where it holds one warmth and brightness you set. You can also flip on a red mode from the swatches without touching the keyboard, and there is a Quit button to close Cindershift entirely.
Right-clicking the tray icon gives you Settings, a Tray visibility option that opens the Windows taskbar settings directly, and Quit Cindershift.
Click the Keys label in the top-right of the settings window to open the bindings panel. Click any action row, then press the key combo you want. You can also press a mouse side button (X1, X2, or middle click) while a row is selected to bind a mouse button instead of a key. Press Escape to cancel a change, or click the X to clear a binding entirely.
You need Rust. On the default x86_64-pc-windows-gnu toolchain you also need a
full MinGW-w64 (gcc and binutils, for example the WinLibs build) on your PATH, so
the HTTPS location lookup can link. Then:
cargo build --release
./target/release/cindershift install
There was a rougher first version of this, a small C# app called RedMode that could never quite get the red right. If you want the backstory on what it did, why it fell short, and how that led here, it's in HISTORY.md.
MIT. Do what you want with it. If you decide to be evil and just change the code to have a blue light only mode, let me know!