Prompt template
Period tracker prompt — copy, paste, build
A privacy-first prompt for a native cycle tracker — calendar log, prediction window, symptom and mood tagging, and reminders. Designed to keep all data on device by default and avoid the trust pitfalls of competing apps that ship cycle data to the cloud.
The prompt
Build a native iOS and Android period tracker with: (1) onboarding to capture average cycle length and last period date, (2) a calendar tab showing past periods, predicted next period window, and fertile window estimates, (3) a daily log screen for flow level, symptoms (cramps, mood, energy), and notes, (4) a quick "log today" CTA on the home screen, (5) a stats tab with average cycle length, average period length, and last six cycles, (6) configurable reminders before predicted period start. Use Expo, React Navigation, twrnc for styling, AsyncStorage with on-device-only persistence, and Expo LocalAuthentication for an optional passcode lock. Privacy posture: no analytics, no cloud sync by default — note that explicitly in onboarding.
Variants
Lite
Build a period tracker with calendar logging, next-period prediction, and a quick "log today" button. Skip symptom tagging and stats.
Pro
Build a period tracker with calendar logging, predictions, symptom and mood tagging, fertile-window estimates, configurable reminders, optional passcode lock, encrypted iCloud / Google Drive backup, and a partner-share toggle.
What you get
- Expo + React Native project ready for Snack live preview
- Calendar log with prediction window
- Symptom and mood tagging
- Cycle and period length stats
- Pre-period reminders
- On-device-only persistence by default
Screens included
- Onboarding
- Home
- Calendar
- Daily log
- Stats
- Settings
Why this prompt works in AppGenie
Period apps are a category where trust and privacy posture matter as much as features. AppGenie scaffolds local-first storage and lets you patch the cloud-sync question separately — wire encrypted iCloud or Google Drive backup later, in chat, without re-running the whole project.
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Open prompt →Period tracker prompt — FAQ
Does the prompt store cycle data in the cloud?
Not by default. Data lives in AsyncStorage on the device. Cloud sync is left as an explicit follow-up so you can pick a privacy posture (none, encrypted iCloud / Google Drive, or your own backend) before flipping it on.
How accurate are the predictions on the first build?
The prompt scaffolds a simple moving-average prediction over the last six cycles. It is intentionally simple — refine the algorithm in chat ("use a luteal-phase-aware model with adjustable variance") and the diff-aware pipeline patches just the prediction module.
Ready to ship a period tracker?
Paste this prompt into AppGenie. The diff-aware multi-agent pipeline produces a real Expo + React Native project you can preview live, iterate in chat, and own end-to-end.