Table Habit: Habit Tracker

Build your micro-habits in the simplest way.
Growth curves and visual charts make every step of your progress visible.
Fully open-source and ad-free, making habit building pure and efficient.

Key Features:

• Scoring system to help you develop your own micro habits
• Supports both positive and negative habits
• Easy-to-use check-in UI
• A quick search and filter to help quickly find past habits.
• Color-coded habits for quick visual distinction
• Import and export habits using a human-readable JSON format
• Optimized for landscape and large-screen devices
• WebDAV sync support for cross-device syncing

Moreover, this app completely open source.

Got source code from: https://github.com/FriesI23/mhabit