PlugBrain is a free, open source Android app that puts a quick math problem between you and your distracting apps.
No ads, no tracking, no internet needed.
Website · Download · How it works · Privacy · Contributing · Community
Most app blockers give you a timer you can tap past without thinking. PlugBrain makes you think.
- 🧮 Friction you have to think through. When it's time for a break, a math challenge stands between you and the app. Solve it to keep going, or take the hint and leave.
- 📈 Adaptive difficulty. Keep coming back and the problems get harder. Stay away and they ease off. Your own habits set the level.
- 🔒 Private by design. No internet permission, no account, no analytics, no ads. Nothing leaves your phone.
- 💚 Free and open source. GPL-3.0, on F-Droid with no anti-features, built in the open with the community.
- Grant a few permissions. PlugBrain needs them to see when a blocked app opens and show the challenge on top. The app explains each one, and Privacy lists why.
- Pick the apps that distract you. The list is sorted by how much you used each app in the last 24 hours.
- Choose how often to be challenged: how many minutes of use before the next challenge.
- Choose your starting difficulty: Beginner, Intermediate or Expert.
- Use your phone as usual. When the time is up, PlugBrain shows a challenge over the blocked app. Answer it to carry on, or tap Leave App.
You can also ask PlugBrain to challenge you as soon as a distracting app opens, not only after a while.
Each challenge you solve makes the next one a level harder. Stay away and PlugBrain drops a level for every two challenge intervals you skip, down to the minimum you chose. More than 40 challenge types cover the range: from simple additions to five-digit sums, subtraction, multiplication tables up to 4×4 digits, squares, and missing-number equations like ? × 7 = 56.
PlugBrain runs on Android 9 and newer. Learn more on the website: plugbrain.app.
Other mirrors
Available in English, Arabic, Chinese (Simplified), Dutch, French, German, Hindi, Japanese, Norwegian (Bokmål), Persian and Russian. Help add yours.
PlugBrain has no internet permission, so it can't send anything anywhere. There are no accounts, ads or trackers, and Google Play's data safety section lists no data collected or shared.
To block apps, it needs a few Android permissions. Each one is explained in the app before you grant it.
| Permission | Why |
|---|---|
| Usage access | Measures time spent in the apps you chose to block |
| Display over other apps | Shows the challenge on top of a blocked app |
| Accessibility service | Detects when a blocked app opens. It never reads content or captures input |
| Ignore battery optimizations | Keeps the blocker running in the background |
Read the full privacy policy.
PlugBrain collects no analytics, so your feedback and contributions are how it gets better. You can:
- Report a bug or suggest a feature in Issues.
- Translate the app and store listing (guide).
- Add a new challenge in a few lines:
./gradlew generateChallenge -PchallengeName=MyChallengescaffolds it for you (guide). - Design screens, store graphics or a video walkthrough (design guide, Figma file).
- Pick up a good first issue or one marked help wanted.
Start with CONTRIBUTING.md. For code, fork the repo, work on a branch, and open a pull request. Before you push, make sure these pass:
./gradlew ktlintCheck
./gradlew detekt
./gradlew testTech stack
- 100% Kotlin, Jetpack Compose and Material 3
- MVVM with the repository pattern, Koin for dependency injection
- Coroutines & Flow, Lifecycle, DataStore
- UsageStatsManager for app usage, Coil for images, Timber for logging
- Tests with JUnit, MockK and Paparazzi screenshot tests
- ktlint, detekt with Compose rules and GitHub Actions for CI/CD
| Module | What's inside |
|---|---|
app |
Screens, blocking service and app wiring |
appusage |
App usage stats and installed apps |
blocking |
When to block and challenge, in plain Kotlin with JVM tests |
challenges |
All math challenge types and their difficulty levels |
datastore |
User preferences |
designsystem |
Shared Compose components, colors and typography |
Share how you use PlugBrain, what works and what doesn't:
- plugbrain.app, the official website
- r/PlugBrain on Reddit
- GitHub Discussions
If PlugBrain helps you, a ⭐ on GitHub or a rating on Google Play helps other people find it.
Built by @msbelaid and contributors from around the world. 🇩🇿 Made in Algeria.
UI design by @HichemDahaoui. Logo by @travis-jeans (style guide).
PlugBrain is free software, released under the GNU General Public License v3.0.