Privacy Policy

Health Data You Enter (Stored Locally on Your Device)

When you use Midline, you may log health information including mood and symptom check-ins, blood sugar readings, meals and estimated calorie intake, insulin doses, medication schedules, supply changes, device events, life events, free-text notes, doctor visit questions, and appointment summaries.

All of this data is stored exclusively in a local database on your device. Midline does not transmit, upload, or sync this data to any server, cloud storage, or third-party service unless you explicitly initiate one of the actions described below.

Data Processed by AI Features (Temporary, Not Retained)

Midline offers optional AI-powered features that require sending some of your health data to a third-party AI service (currently Google Gemini) for processing. These features include Ask My Health (conversational questions about your logged data), appointment summary generation, and enhanced meal analysis.

When you use these features, the relevant portion of your health data is sent to the AI service to generate a response. This data is processed in real time and is not stored, retained, or used for training by the AI service provider. The AI service receives only the data necessary to fulfill your specific request — not your entire health history.

You can use Midline fully without ever activating these features. All core logging, tracking, and manual export functions work entirely offline.

Analytics Data (Anonymous, No Health Information)

We collect anonymous usage analytics to understand how people use the app and to identify crashes and bugs. This includes information such as which screens are visited, feature usage frequency, app crashes and error reports, device type and operating system version, and app version.

This analytics data never includes any health information you’ve entered. It is not linked to your identity. We use this data solely to improve the app.

Data We Do NOT Collect

We do not collect your name, email address, or any personal identifying information (Midline does not require an account). We do not collect your location. We do not access your contacts, photos, or other apps. We do not track you across other apps or websites. We do not sell, share, or monetize any data to third parties for advertising or any other purpose.

On Your Device

All health data is stored in an encrypted SQLite database within Midline’s sandboxed storage on your iPhone. This means only Midline can access the data — no other app on your device can read it. The database is included in your standard iPhone backup (iCloud or local), so your data transfers automatically when you set up a new device from a backup.

When You Export

You can export your data at any time through Settings. Export formats include PDF (for appointment summaries), CSV (for raw data), JSON (for full data portability), and Markdown. When you export, the file is generated on your device and shared through the iOS share sheet. You control where the file goes — email, AirDrop, Files, or any other destination. Midline does not retain a copy of exported files.

When You Delete

You can delete individual entries at any time. You can also delete all of your data through Settings, which permanently removes the local database. Since we don’t store your data on any server, deletion is immediate and complete. There is nothing for us to delete on our end because we never had it.

How It Works

When you use an AI-powered feature, Midline sends the minimum necessary data to our processing service, which forwards it to the AI provider. The AI generates a response, which is returned to your device. No health data is stored at any point in this chain — not by our service, and not by the AI provider.

What Gets Sent

For Ask My Health: your recent health entries relevant to the question you asked, formatted as anonymized context. For appointment summaries: your entries within the selected date range and your doctor questions. For enhanced meal analysis: the photo you took of your meal.

What Doesn’t Get Sent

Your full health history is never sent in a single request. Your name and personal details are not included. Only the data necessary to answer your specific question or generate your specific request is transmitted.

On-Device AI Features

Some AI features run entirely on your device using Apple’s machine learning frameworks. Blood sugar photo reading (OCR) and basic meal photo recognition process photos locally on your iPhone. These features work offline and never send your photos or data anywhere.