On-Device Health AI That Actually Answers Questions — No Cloud, No Upload
Your Apple Health data holds years of readings — heart rate, sleep, HRV, steps, workouts. Most "health AI" apps just send it all to a server. Here's one that keeps it on your phone and answers real questions with the numbers to prove it.
You've got years of Apple Health data on your phone. Heart rate, sleep stages, HRV, resting pulse, step counts, workouts — over 190 metrics, with readings going back months or years.
What can you actually do with it?
Most people open the Health app, scroll through a few charts, and close it. The data is there, but it's locked inside a grid of screens. You can't ask it a question. You can't say "how's my sleep trending this month?" and get a real answer.
That's the gap an on-device health AI fills. And the privacy part isn't optional — it's the whole point.
What "on-device" actually means for your health data
Here's the problem with cloud-based health AI: you have to upload your data to use it. Every single metric — your resting heart rate, your sleep patterns, your HRV — gets copied to someone else's server. The company promises to "protect your privacy" in a blog post, but your data still leaves your phone.
On-device processing flips that. The AI model runs on your iPhone. Your health data never leaves the device. The question, the computation, the answer — all local. No upload, no cloud account, no server in the path.
That's what Health Export AI does. It reads Apple Health read-only, answers questions about your data on-device, and shows you exactly how it got each answer. You can also export to your own AI agents over MCP — but the core experience never needs to touch the internet.
Real questions you can ask
The chat is a text field at the bottom of the screen. You type a question in plain English and get an answer in seconds. The app uses a deterministic "Guided" engine for most queries (runs on every iPhone, no network) and a local language model for free-form questions where available.
Try these:
- "How's my sleep trending this week vs last?" — It pulls your sleep samples for both periods, computes the average, and shows the delta. You see the numbers: "7.2h this week vs 6.8h last week (+5.9%)."
- "Compare my HRV this month to last month." — HRV is a lagging recovery signal. The app computes the mean, the trend direction, and the variance. If your HRV dropped 12% month-over-month, you see it in a chart with the exact values.
- "What's my resting heart rate been doing on weekends?" — It filters weekend vs weekday readings, computes the average, and tells you whether your weekends are actually more relaxed.
- "Show me my step count for the last 14 days." — Returns a clean list or chart with the date, step count, and daily average.
Every answer comes with a provenance card — the headline number in large type, an inline chart, and a tappable strip that shows exactly which samples, date range, and computation produced the result. No "AI vibes." You see the data that drove the answer.
Why provenance matters more than you think
This is where most health AI apps fall apart. They return a nice-sounding sentence — "Your sleep quality has improved this week!" — but you can't see the numbers behind it. Which metric? Compared to what baseline? Show me the actual data.
Health Export AI's provenance card is the answer to that. Every computed result shows:
- The metric and date range queried
- The raw sample count and computation (mean, median, trend, delta)
- A chart or sparkline of the underlying data
- A tappable strip that expands to individual samples
You can verify the AI's work. If it says your HRV averaged 62 ms this week, you can tap through and see the individual readings — 58, 64, 67, 61, 59 — and confirm the math. It's the difference between trusting an app and knowing you're right.
Provenance is the differentiator. The nearest paid competitor's #1 complaint across App Store reviews is untraceable, self-contradicting AI stats. They say "your recovery is good" one day and "your recovery is poor" the next — and you can't tell which is right because neither shows the data. Provenance makes the answer auditable.
Also: the Weekly Health Brief
You don't have to open the app to get value. The Weekly Brief is an on-device digest that arrives as a notification + in-app card. It summarizes your week's trends — sleep, HRV, resting HR, steps, workout load — and compares them to the previous week. Same provenance cards. Same local computation. It's the renewal engine: the app shows up for you.
No server generates the brief. No cloud processes your data. Just your iPhone, running the same numbers you'd compute yourself if you had the time.
The other side: export to your own AI agents
If you're the kind of person who runs Claude, Cursor, or opencode on your own machine, the on-device chat isn't the only way in. Health Export AI also exports your 190 metrics as clean JSON to a destination you choose — iCloud Drive, a local folder, your LAN, or a webhook — and ships a zero-dependency MCP server that lets any MCP-aware agent query your live data.
That means you can ask Claude the same questions about your sleep and HRV, running on your Mac, against the same local data. The MCP server is read-only, open-source, and makes zero network calls. It's the developer counterpart to the on-device consumer app.
For the full setup, see Connect Apple Health to Claude via MCP.
What about the other on-device health apps?
There are a few apps in this space now — Risi.ai, Metrya, eutonia, and Sifa all claim some form of on-device processing. But none of them bridge to MCP. None of them let you take your data out and feed it to the AI agents you already use. And none of them show full provenance on every answer.
Health Export AI is the only app that gives you both: a private on-device chat with auditable answers, and a live data pipeline to your own agents. You don't have to choose between privacy and utility.
Pricing and what you get
The app is straightforward. Export and raw MCP access are a $2.99 one-time unlock — permanent, never metered. The on-device intelligence (Ask/Pro Chat with provenance cards, the Weekly Brief, and live agent tools) is Pro at $5.99/month or $39.99/year. No accounts, no tracking. The app doesn't have a server to call home to.
You can start with the free tier, grant HealthKit read access, and see the data flow. The on-device chat is available on a trial basis so you can test it before committing.
Your data. Your phone. Your AI.
Ask real questions about your Apple Health data — answered on-device, with numbers you can verify. Free 7-day trial, no account, nothing on our servers.