Streakly Habit Tracker

Overview

Streakly helps users build consistent habits by tracking daily check-ins with streak counting and visual progress. The calendar heatmap shows consistency at a glance, inspired by GitHub's contribution graph.

All data is stored locally with no accounts, servers, or syncing — making it the most private habit tracker available.

Features

• Habit Management: Create habits with name, frequency (daily/weekly), and color
• Daily Check-In: One-tap completion for each habit
• Streak Counting: Current streak and longest streak per habit
• Calendar Heatmap: GitHub-style contribution graph showing consistency
• Streak Goals: Set target streaks with progress indicators
• Habit Categories: Group habits by area (health, work, personal)
• Statistics Dashboard: Completion rate, best habits, weakest days
• Reminder Notes: Add context notes to any day
• Data Export: JSON backup for migration

Architecture

habit-tracker.html

├── <style>       → Heatmap grid, habit cards, dashboard layout

├── <main>        → Habit list, calendar heatmap, stats, add/edit modal

└── <script>      → Streak calculations, heatmap rendering, statistics, localStorage

Tech Decisions

Real-World Impact

Habit tracking apps like Streaks and Habitica require accounts and cloud sync. Streakly provides the core habit tracking loop — check in, build streaks, see progress — without any data leaving the device. For users concerned about behavioral data privacy, this is the only option.

Measured Results

• Check-in completes in < 50ms
• Heatmap renders for 365 days in < 100ms
• Streak calculations accurate across month boundaries
• Handles 20+ habits with daily data for a year

Conclusion

Streakly shows that habit tracking doesn't require behavioral surveillance. The combination of streak psychology, visual heatmaps, and local-only storage creates a motivating yet private habit building tool.