With no coding background, they built a private cycle-tracking app in two hours

Private Offline Cycle Tracking App   Project Description   I created a private, offline Android app for basal body temperature measurement and menstrual cycle tracking, based on the Fertility Awareness Method (FAM).   The idea came from my own frustration with existing cycle-tracking apps. Many require an internet connection, collect or synchronize sensitive personal data, contain advertising, or offer so many additional features that the actual cycle tracking becomes unnecessarily complicated. I wanted to create something different: a simple, focused tool that helps women observe their cycle and understand their biology while keeping their personal data under their own control.   I had been using the Notes app on my phone to record my own observations, but I could not easily visualize the data, see which day of my cycle I was on, or generate temperature graphs without transferring the information to paper and creating the graphs myself. I wanted a digital version that was simple, intuitive, and matched the way I personally wanted to track my cycle.   Achievements   * Designed and built my first Android application completely from scratch. * Created a fully functional offline cycle-tracking application without previous Android development experience. * Implemented local-only data storage with no internet permissions, accounts, cloud synchronization, or external APIs. * Created daily tracking for basal body temperature, measurement time and waiting time, sensations, cervical mucus observations, menstrual bleeding, underwear stains, dreams, sleep times, and intercourse. * Implemented automatic moon-phase calculation directly from the date, without requiring an internet connection or API. * Created a temperature graph organized by cycle, with the first day of bleeding defining the first day of the cycle. * Created a calendar view showing both calendar dates and cycle days. * Added local data export and import so users can transfer their own data when changing phones. * Reached approximately 80% of my intended final version in around 1.5–2 hours of development.   The application currently works successfully in the Android Studio simulator. My next step is testing it on a physical Android phone and making further refinements based on real-world use.   Tools   * Claude Code and Claude Chat - AI-assisted coding, brainstorming, application architecture, implementation, debugging, and testing. * Android Studio - development environment and Android simulator. * Fertility Awareness Method resources - used to guide the terminology and structure of cycle observations.   Methodology   I started with a personal problem and defined the features I actually wanted rather than trying to reproduce the large number of features found in existing cycle-tracking applications.   I then used Claude Code as an AI development partner. I described my idea and requirements, and Claude helped translate them into the application architecture and code. I used Android Studio to run and inspect the application in the Android simulator. Claude Code assisted with debugging and iterative improvements as issues appeared.   The process was essentially:   **Idea → feature definition → AI-assisted architecture → coding → testing in Android Studio → debugging → refinement**   A key design principle throughout the process was privacy. I deliberately designed the application without internet permissions, accounts, cloud storage, or external APIs so that the user's cycle information remains stored locally on their device.   Learnings   The biggest learning was not technical, it was realizing what I am capable of creating with AI.   Before starting this project, I believed that building an Android application required a developer with specialized programming experience. I had no Android development experience and had never built an app before. Within approximately two hours, I was able to turn an idea into a functioning application by working collaboratively with Claude Code.   This changed my perception of what is possible with AI-assisted creation. Instead of AI simply being a tool for generating information, I experienced it as a development partner that could help me move from an idea to a tangible product very quickly.   The project also taught me the importance of starting with a clear problem and personal use case. Because I knew exactly what I wanted the app to do, and, equally importantly, what I did NOT want it to do, I could keep the product simple and focused.   Most importantly, this project made me excited to experiment with building more things in the future. It showed me that I don't necessarily need to wait until I have all the technical skills myself before bringing an idea to life.   Relevant URLs   Screenshots of the application are provided in the accompanying document.   The application is currently a private development project and is not yet publicly published. But if testing phase works well, I plan to work together with my Fertility Awareness Coach and distribute it to the women she works with and make it available for the public use.