Blink

Smart 20-20-20 eye break reminder
for macOS and Windows

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Why open source? Blink needs Accessibility permission to work — that's a lot of trust. We made it open source so you can see exactly what we do with it: read input timing, never content. No analytics, no telemetry, no network calls. Every line is right here.

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Every 20 minutes of screen time, look at something 20 feet away for 20 seconds. Optometrists have recommended this since the 90s. The problem isn't the rule — it's the apps.

They interrupt you mid-thought. They fire a popup while you're in a meeting. They nag you when you already walked away 2 minutes ago. They don't care that you're deep in a coding session and interrupting now will cost you 23 minutes to get back into flow.

Blink is different. It watches how you work (never what) and breaks come at the right moment.

Install

macOS

curl -fsSL https://raw.githubusercontent.com/D4G4/blink/main/install.sh | bash

Downloads the latest release, installs to /Applications, and handles quarantine automatically.

macOS

brew tap D4G4/blink
brew install --cask blink

Update later with brew upgrade --cask blink.

macOS

1. Download Blink.dmg from the latest release
2. Open the DMG, drag Blink to the Applications folder
3. Before first launch, run this in Terminal to clear the quarantine flag:

   xattr -cr /Applications/Blink.app

4. Launch Blink — it appears as an icon in your menu bar
5. Grant Accessibility when prompted (required for smart detection)

The xattr step is needed because the app isn't notarized with Apple (we're open source, not paying $99/year for a certificate). Homebrew install handles this automatically.

1. Download Blink-x64.exe from the latest release (or Blink-arm64.exe for ARM devices)
2. Run the exe — Windows SmartScreen may warn "Unknown publisher", click More info → Run anyway
3. Blink appears as an icon in your system tray
4. Right-click the tray icon for Settings, Take Break Now, or Quit

The SmartScreen warning appears because the app isn't code-signed. It's a one-time click — the app works normally after that.

What makes it smart

• 🧠 Flow detection — Monitors typing rhythm and app switching. When you're in deep focus, the timer extends from 20 to 30-40 minutes.
• ⏸️ Natural pause waiting — Doesn't interrupt mid-keystroke. Waits for a 6-second gap in your input — a natural thought boundary.
• 🚶 Walk-away detection — Left your desk for 3+ minutes? That counts as a break. Timer resets silently.
• 🎬 Video awareness — Watching YouTube or Netflix? Timer pauses — you're already resting your focus.
• 🎙️ Meeting detection — Mic or camera active? Timer pauses. No interruptions during calls.
• 🤖 Agent workflow aware — Waiting for an AI response while scrolling? Timer keeps running. Sitting perfectly still for 3 minutes? That's a walk-away.

How it works

You work normally
        |
    20 minutes pass (or 30-40 in flow)
        |
    Toast appears in corner: "Break in 3s"
        |
    Fullscreen overlay: look away for 20 seconds
        |
    [esc] skip    [->] extend 20s
        |
    Timer resets. Cycle continues.

The app lives in your menu bar (macOS) or system tray (Windows). Click to see your timer, flow state, and break stats.

Themes

Choose during onboarding or change anytime in Preferences.

Peach · Sage · Sand · Midnight · Mono

Mono is dark-mode-aware — colors invert automatically.

Privacy

Blink monitors input timing (keystroke cadence, app switch frequency, mouse patterns) to detect flow state. It never logs:

• What you type
• Which apps you use
• Window contents or titles
• Any personal data

All data stays local (~/Library/Application Support/Blink/ on macOS, %LOCALAPPDATA%\Blink\ on Windows) as daily JSON files. The only network call is an optional update check against GitHub Releases. No analytics. No telemetry.

The 20-20-20 rule

Coined by optometrist Dr. Jeffrey Anshel in 1991:

Every 20 minutes, look at something 20 feet away, for 20 seconds.

Your blink rate drops from 15/min to 4/min during screen work. This causes dry eyes, headaches, and blurred vision. A 20-second break lets your eye muscles relax and reset.

Building from source

CI builds run automatically on every push via GitHub Actions. Tagged releases (v*) build both platforms, create a GitHub Release with all artifacts, and update the Homebrew cask.

macOS

cd blink-macos
brew install xcodegen
xcodegen generate
open Blink.xcodeproj   # Cmd+R to run

Windows

Requires .NET 10 SDK and Windows App SDK.

cd blink-windows
dotnet build
dotnet run --project src/Blink.App

Or open Blink.Windows.slnx in Visual Studio 2022+.

Tests

# macOS — 85 tests
cd blink-macos/BlinkCore && swift test

# Windows — 74 tests (runs on Mac too)
cd blink-windows && dotnet test

Architecture

blink-macos/                    blink-windows/
├── BlinkCore/                  ├── Blink.Core/
│   ├── FlowDetection/         │   ├── FlowDetection/
│   │   ├── 5 signal scorers   │   │   ├── 5 signal scorers
│   │   ├── FlowScoreCalc      │   │   ├── FlowScoreCalc
│   │   └── FlowStateMachine   │   │   └── FlowStateMachine
│   ├── Timer/                  │   ├── Timer/
│   └── Compliance/             │   └── Compliance/
├── Blink/                      ├── Blink.Platform/
│   ├── Platform/ (CGEventTap)  │   ├── WinInputMonitor (hooks)
│   ├── MenuBar/                │   ├── WinAppMonitor
│   ├── Overlay/                │   └── WinIdleDetector
│   ├── Onboarding/             └── Blink.App/
│   ├── Settings/                   ├── TrayIcon/
│   └── Theme/                      ├── Overlay/
└── project.yml                     └── Theme/

The core logic (flow detection, timer, compliance) is platform-agnostic. Platform adapters implement 4 interfaces:

• InputEventSource — keyboard/mouse timing
• AppActivitySource — app switches, window changes
• IdleStateSource — time since last input
• ContextSource — meetings, video, fullscreen

License

MIT