Is health data a legal problem for an indie app?

It is sensitive data, so the safe default is on-device-first storage, an explicit privacy policy, and a working delete-everything button. If you sync to a server you take on much more — and if you market to clinicians or make treatment claims you can land in medical-device or HIPAA territory. Keep it a personal logbook.

Should the app suggest what is causing the symptoms?

Show correlations, never conclusions. "Your average severity was 6.1 on days you tagged poor sleep versus 4.2 on other days" is useful and honest. "Poor sleep is causing your flare-ups" is a medical claim you cannot support and should not ship.

How to Build a Symptom Tracker App with AI (2026)

What a symptom tracker app needs

Daily log with severity sliders per tracked symptom
Tag triggers and context — food, sleep, stress, medication
Timeline view with severity over weeks
Simple correlation view: severity on days with vs without a tag
Reminder to log at a chosen time
Doctor-ready summary export for a date range

The screens

Screen	What it does
Today	Log severity for each tracked symptom plus tags, in one screen
Timeline	Severity over time with logged tags marked on the chart
Patterns	Average severity on days with a tag vs without it
Symptoms	Add, rename, or archive what you track
Export	Date-range summary to share with a clinician
Settings	Reminder time, data export, delete all data

The data model

Symptom: name, scaleMax, isArchived
LogEntry: date, note
SymptomReading: logEntryId, symptomId, severity
Tag: name, category
EntryTag: logEntryId, tagId

The build prompt (copy this)

Paste this into ShipNative and it becomes a working React Native app with these screens, navigable in a live preview, in about two minutes:

“A symptom tracker for people managing a chronic condition. Users pick which symptoms to track, then log severity for each one daily on a 0-10 scale and tag the day with context like food, poor sleep, stress, or a medication change. Screens: Today (fast logging, under ten seconds), Timeline (severity chart over weeks with tags marked), Patterns (average severity on days with a tag versus without), Symptoms (manage tracked items), Export (date-range summary to share with a doctor), Settings (daily reminder, export, delete all data). Works offline. Never present the patterns view as a diagnosis — label it as an observation.”

Then iterate with small, screen-specific prompts (“make the primary button bigger”, “add an empty state”), preview on your own phone, and export the full Expo project whenever you want. The full method: how to build an app with AI.

How it makes money

Subscription ($4–7/mo) gated at the Patterns view and export, with unlimited logging free. Niche versions — migraine, endometriosis, IBS, long COVID — convert far better than a generic tracker because the symptom list and tags are already right.

Implementation and the revenue math for every model: how to make money from an app. When you’re ready to ship: App Store and Google Play publishing guides.

Build it now

The prompt above is free to run at shipnative.dev — working symptom tracker app on your phone today, full code export, no credit card.

How to Build a Symptom Tracker App with AI