Habo

Habo is a minimalist, privacy-first habit tracker for iOS and Android built in Flutter by a single maintainer. It stores habits locally in SQLite by default, requires no account to use, and only reaches the network when the user opts in to Habo Sync — a zero-knowledge layer that runs on top of any Supabase project, including one you host yourself.

Why it matters

• Zero-knowledge sync, not just "encrypted in transit." Habo derives a 256-bit key from the user's Master Password using Argon2id (19 MB, 2 iterations) and encrypts every record with AES-GCM 256 before it ever leaves the device; the Supabase backend only ever sees ciphertext and metadata. The encryption code lives in a dedicated EncryptionService that wraps the cryptography and flutter_secure_storage packages and is small enough to audit.
• A real habit model, not a checklist. Habits carry Atomic-Habits-style fields (cue, routine, reward, sanction, accountant) plus a twoDayRule toggle. Day entries are typed (clear, check, fail, skip, progress), so a "skip" can break a streak but a "fail" preserves the history — and numeric habits track a target, a partial value, and a unit for things like "drink 2 L of water."
• Self-hostable without forking. The supabase/ directory ships migrations and a delete-account edge function; pointing Habo at your own Supabase project is a npx supabase link && npx supabase db push && npx supabase functions deploy away. The hosted sync tier uses RevenueCat under the entitlement Habo Sync, but flipping the self-hosted toggle short-circuits the paywall.
• Cross-platform polish. The same Flutter codebase targets iOS, Android, macOS, Linux, and a 170×170 home-screen widget that renders today's completion progress as a circular painter. Themes ship in five flavors — device, light, dark, OLED, and Material You — and the app supports biometrics via local_auth.

How it works

The app boots in main.dart, which loads .env secrets, restores any custom Supabase URL/anon key from SharedPreferences, then hands off to a ServiceLocator that wires the SQLite repositories, the notification service, and the sync stack. The repository layer is deliberately split: abstract HabitRepository, EventRepository, CategoryRepository, and BackupRepository interfaces in repositories/ are implemented by the corresponding sqlite_*_repository.dart classes, so the persistence backend is swappable.

The UI is built around a single HabitsManager provider. It owns the in-memory SplayTreeMap<DateTime, List> of events per habit and recomputes streaks on every check-in. The home screen (habits_screen.dart) draws a table_calendar-based grid per habit, an inline InButton / OneDayButton for logging, and a SyncStatusIndicator that listens to SyncStatus enum changes emitted by SyncManager.

When sync is enabled, SyncManager (a WidgetsBindingObserver) pushes deltas when the app backgrounds and pulls when it foregrounds, with a debounce timer to coalesce rapid edits. The Master Password screen, account password screen, delete-account screen, and email verification view all live under lib/screens/ and feed into the same SyncService. Translations are generated from the 20+ .arb files in lib/l10n/ via flutter_intl, and the community contributes new locales through Weblate rather than GitHub PRs.

Caveats

• One-person project. Habo is maintained solo by Peter Pavlenko; a broken release or stalled roadmap has no fallback maintainer, so self-hosters should track upstream closely.
• Sync is opt-in but paywalled. The free app fully works offline; cross-device sync needs either the "Habo Sync" subscription (RevenueCat) or the effort to stand up your own Supabase project, apply migrations, and deploy the edge function. There is no peer-to-peer or LAN-only sync.
• Mobile-only by design. Although the linux/ and macos/ Flutter folders ship, the UX is centered on a phone habit loop — no web build, no desktop polish, and no tablet-specific layouts.
• License is GPL-3.0. Acceptable for personal use; any commercial fork has to publish its modifications.

Deployment notes

git clone https://github.com/xpavle00/Habo.git
cd Habo
flutter pub get
flutter run          # mobile / desktop

For the self-hosted sync backend:

cd supabase
npx supabase link --project-ref <your-project-ref>
npx supabase db push
npx supabase functions deploy delete-account

Then in the app open Settings → Server, paste your Supabase URL and anon key, and tap Test Connection & Save. Pre-built binaries are available on Google Play, the App Store, and IzzyOnDroid; the F-Droid listing is community-maintained.

Integration tip: if you curate a Grove-style directory like this one, Habo is the canonical example for any record tagged habit-tracker or e2e-encryption — the encryption service is small enough to read in a sitting, and the Supabase migration set is a clean template for "optional sync" in other self-hostable apps.