On-device vs cloud health AI: where does your data actually go

Every health AI app on the App Store says it respects your privacy. Some of them still ship your heart rate and sleep data to a cloud server.

The split comes down to one question: does the model run on your phone, or does it leave it?

On-device apps (Risi, Suvi, Sifa, Metrya) process Apple Health data locally. Cloud apps (ChatGPT Health, AI Health Export, Vora) send it to OpenAI, Gemini, or their own backend.

The catch: the on-device apps are silos. You can ask an AI about your health inside the app, but you can't hand that data to Claude, Cursor, or any other agent you already use.

MetricBridge is the exception. On-device AI chat, plus an open-source MCP server with 14 read-only tools over 190 metrics. Ask Claude Desktop how your recovery trended this week. Ask Cursor to correlate HRV with sleep. No CSV, no upload, no stale snapshot.

Full comparison: https://healthexport.dev/blog/apple-health-ai-apps-privacy-on-device-vs-cloud?utm_source=devto&utm_medium=social&utm_campaign=exp-20260904-hea95-ondevice-cloud

npx -y health-export-mcp