Tau.

The most comprehensive AI analysis of your Apple Health data.
218 metrics, computed on your device, then explained in plain language by the AI model of your choice.

Tau. is entirely free. Pro bono. No paywall, no subscription, no accounts, no ads.

Download on the App Store Coming soon
Health Data Export

AI Analysis

What Tau. is

Free
Non-profit.
Fully private
Nothing leaves your device unless you want it to.
Mathematically sound
Each metric is analysed with statistics chosen to fit its own distribution.
Simple by design
Minimal input, meaningful output.

What you can do with Tau.

Visualise Your Data
View your data with intuitive charts.
Explore Patterns
With advanced statistics, chosen to suit each metric.
Chat with AI
Ask questions in plain language.
Export a Report
Generate a report or export your raw data.
Built-in AI Chat

Chat with your health data

Your Health app data, conversational. Your device does the maths; the AI reads those results and answers your questions in plain language — something no fixed chart can do.

Your health data connects to 4 AI providers and 50+ AI models via the built-in AI chat Learn about AI Chat →
Privacy boundary

Clear control over what leaves your device

Every figure is computed on your device. Nothing is sent anywhere unless you deliberately send it.

Where your health data can go: analysed on device, or sent only to the AI provider you chose
Coverage

218 metrics

The power of Tau. is in cross-metric questions — activity, workouts, heart, sleep, nutrition, reproductive health, clinical symptoms, etc. On top of those 218 come 5 profile characteristics (such as age and blood type), and one further metric for each medication you choose to share.

Check every metric →
Analysis

Trends, cycles and correlations, computed on-device

Beyond chat and export, Tau. has a built-in Analysis tab — no AI, no cloud, just your numbers, run through the statistics each kind of health data actually calls for.

Evolution
How has each metric changed since the period before? Compare the weeks, months or years of your choice.
Correlation
Do two metrics tend to move together? See whether one tends to rise when the other rises or falls, even when the link isn't proportional.
Rhythm
Does a metric follow a pattern that keeps repeating, like weekends that differ from weekdays or summers from winters?
Variability
How steady is a metric? See how widely its values spread and how much it jumps from one reading to the next, by hour, day, week or month.

iPhone

Tau. home screen on iPhone showing the 218 Apple Health metrics available for analysis Tau. metric detail view with an on-device chart of a health metric over the full history Tau. Analysis tab showing evolution, correlation, rhythm and variability of health metrics Spearman correlation between two Apple Health metrics, computed on device in Tau. Tau. built-in AI chat answering a question about personal Apple Health data in plain language Tau. AI provider and model picker, with export options for a health report or raw data