Change Detection

Know when a web page changes. Change Detection monitors pages from your device, saves their history, and notifies you of updates.

Free and open source. No account, cloud service, or first-party tracking.

• Compare readable text, HTML, images, or screenshots.
• Watch a specific part of a page and ignore the rest.
• Schedule background checks or check on demand.
• Review saved versions and see what changed.
• Use Turbo for short sessions with more frequent checks.

Android is the main app. Screenshot capture and background monitoring are Android features. Desktop monitoring runs while the app is open; iOS is still in development. Android screenshots can reuse a browser login; text and source monitoring cannot.

The app supports English, Spanish, Italian, Portuguese, German, Hindi, Bengali, and Simplified Chinese. It follows your device language; Android 13 and newer also let you choose an app language in system settings.

For Android, install SDK platform android-37.2. Gradle manages its own version and the JetBrains Runtime 25 toolchain.

# Build the Android debug APK
./gradlew :androidApp:assembleDebug

# Run the desktop app with hot reload
./gradlew :shared:hotRunDesktop

# Package the desktop app for your current OS
./gradlew :shared:packageDistributionForCurrentOS

# Run the browser demo
./gradlew :webDemo:wasmJsBrowserDevelopmentRun

For the marketing website, use Node 26.11.1 and pnpm 12.11.2:

cd website
pnpm install --frozen-lockfile
pnpm dev

For iOS, open iosApp/iosApp.xcodeproj in Xcode; simulator builds require Apple silicon. Edit its layered app icon in Apple's Icon Composer.

Desktop packages use the same icon on macOS, Windows, and Linux. macOS packaging requires Xcode for the layered icon.

./gradlew spotlessCheck :shared:testAndroidHostTest :shared:desktopTest :androidApp:lint

For the website, run pnpm lint and pnpm build from website/.

Database upgrades preserve history from the original public schema (1) to schema 4. Retired development databases may reset their data.

Publishing uses Gradle Play Publisher. Set CHANGEDETECTION_SIGNING_PROPERTIES to an external signing file containing storeFile (absolute path), storePassword, keyAlias, and keyPassword. Set CHANGEDETECTION_PLAY_CREDENTIALS to a Play service-account JSON file, and increase versionCode before uploading.

# Upload a draft to the internal track
./gradlew -PplayPublishing=true :androidApp:publishReleaseBundle

See Privacy and the Apache 2.0 license.