Android/iOS: We've featured quite a few habit-building apps and tricks over the years. HabitBull packs all those principles in a gorgeous, free, cross-platform app.
The app has a simple interface with which you can set up a new habit that you want to track or form, and add things to it like reminders, the ideal 66 day duration, a "Don't Break the Chain" streaks calendar, motivational phrases, and more.
HabitBull also intelligently puts all your data in beautiful graphs, much like Loggr for iOS. The cool part is that HabitBull also works on Android, and the Pro version can sync data between your Android and iOS devices (for us cross-platform nerds).
Finally, there's also a discussion forum built into the app, so you can get advice or offer a few tips on how to follow through on certain topics.
The free version of HabitBull lets you track up to five habits and offers reminders, while the premium version allows for 100 habits, cloud backup and syncing, widgets, and the ability to export your data to CSV files.
HabitBull for Android (Free, $4.49 for Premium) [Google Play Store]
HabitBull for iOS (Free, $4.49 for Premium) [iTunes App Store]