Privacy Policy

Summary

Who we are

Neutrino (“Neutrino”, “we”, “us”) is a free, open-source Android application and this accompanying website at neutrino.ytosko.dev, maintained by the Neutrino project (ytosko) and its contributors. The source code is publicly available at github.com/Ytosko/Nutrino under the GNU General Public License v3.0, so anyone can verify the statements in this policy.

This policy covers the Neutrino app as distributed by the project (for example through Google Play or the project's GitHub releases) and this website. Modified versions built and distributed by others are the responsibility of whoever distributes them.

Data the app handles

The app processes the following data on your device, only to provide its features:

To take a meal photo, Neutrino opens your phone's camera app. It does not request the camera permission itself. To choose an existing photo it uses the Android photo picker, so it never gets access to your whole gallery. Photos are resized and stripped of metadata (including location) on your device before they are sent. Temporary camera files are deleted after analysis.

AI providers

To analyze a meal, the app sends the photo and a text prompt directly from your device to the provider you configured, such as Google (Gemini API) or OpenAI. These requests are made with your own API key and are governed by your agreement with that provider, including their data usage and retention policies. Neutrino has no access to these requests or responses beyond what is displayed in the app on your device.

Provider terms differ. For example, some free tiers may use submitted content to improve the provider's services, while paid tiers may not. Please review your provider's current terms before use:

• Google Gemini API: ai.google.dev/gemini-api/terms
• OpenAI: openai.com/policies

Neutrino does not send your nutrition history, Health Connect data or any other personal data to AI providers. Only the photo you are analyzing and the settings needed for the prompt (such as your cuisine preference and local time) are sent.

Health Connect

With your permission, Neutrino writes data to Health Connect, Android's on-device health data store. Neutrino requests only these permissions:

• Write nutrition: to save the meals you approve (food name, carbohydrates, protein, fat, energy and related nutrients, meal type and time).
• Write hydration: to save water intake you log.

Neutrino does not read other health data, such as heart rate, sleep, activity or blood glucose. If a future version asks for additional access, for example to read back nutrition records it previously wrote so it can restore your history, the app will ask for your permission first and this policy will be updated beforehand.

Data obtained through Health Connect is used only to provide Neutrino's features to you. It is not used for advertising, not sold, not shared with third parties, and not used to determine credit-worthiness or for lending purposes. You can review or revoke Neutrino's permissions and delete its data at any time in Health Connect settings.

Google Drive backups (optional)

If you choose to connect your Google account, Neutrino requests the https://www.googleapis.com/auth/drive.appdata scope. This allows the app to read and write only its own private application data folder in your Google Drive. That folder is hidden from your Drive file list. Neutrino cannot see, open, change or delete any of your other Drive files.

• What is stored: backup files containing your settings, meal history and, only if you enable it, your API key.
• Encryption: backups are encrypted on your device with a password you set before they are uploaded. Neutrino's maintainers have no access to your Drive, your backup files or your password.
• When: on the schedule you choose (daily, weekly or monthly) or when you tap “Back up now”.
• Your Google account email is shown in the app so you know which account holds your backup. It is not sent anywhere else.
• Revoking access: disconnect in the app, or visit myaccount.google.com/permissions. To delete stored backups, use the in-app “Delete Drive backup” option or, in Google Drive on the web, open Settings → Manage apps → Neutrino → Delete hidden app data.

Google API Services: Limited Use disclosure

Neutrino's use and transfer to any other app of information received from Google APIs will adhere to the Google API Services User Data Policy, including the Limited Use requirements. Specifically, data accessed through Google APIs is used only to provide the backup and restore features you request; it is not transferred to others, not used for advertising, and not read by humans. The only exception is when you give explicit permission, when it's needed for security purposes, or when required by law.

What we don't collect

• No accounts, sign-ups or user profiles.
• No analytics, telemetry, advertising identifiers or tracking SDKs.
• No crash-reporting services. If you report a bug, you choose what to share, for example in a public GitHub issue.
• No location data.
• No selling or sharing of personal data with anyone.

App stores such as Google Play may collect data under their own policies (for example, install statistics). That data is governed by the store's privacy policy.

This website

This website is a static site. It uses no cookies, no analytics and no third-party scripts, and it serves its own fonts, so your browser doesn't contact other services when you visit. Our web server is configured not to keep access logs. The hosting infrastructure necessarily processes your IP address transiently to deliver the page.

Retention & deletion

• On your device: app data remains until you delete it in the app, clear the app's storage or uninstall it.
• Local backup files: remain where you saved them until you delete them.
• Health Connect: records Neutrino wrote remain in Health Connect even after uninstalling, until you delete them in Health Connect settings.
• Google Drive: the latest backup remains in Neutrino's hidden folder until you delete it as described above.
• AI providers: retention is governed by your provider's policy.

Security

API keys are encrypted with Android Keystore and excluded from Android's automatic cloud backup. Backups are encrypted on your device before they are written or uploaded. All network requests use HTTPS. Because the code is open source, security researchers can audit it. Please report vulnerabilities privately to privacy@ytosko.dev.

Children

Neutrino is not directed to children under 13 (or the minimum age in your country), and we do not knowingly process children's data. Because we collect no data, there is nothing for us to delete, but if you have concerns please contact us.

Your choices

Because your data stays on your device and in accounts you control, you are always in control. You can view, export or delete your data in the app; revoke Health Connect permissions; disconnect Google Drive; delete backups; or uninstall the app. Depending on where you live (for example under the GDPR), you may have rights to access, correct or erase personal data. Since the Neutrino project holds no personal data about you, these rights are exercised directly through the controls above. You may still contact us with any questions.

Changes to this policy

If we change this policy, we will update the “Last updated” date above and, for material changes, note them in the app's release notes. The full history of this page is visible in the project's public repository.

Contact

Questions or requests about privacy: privacy@ytosko.dev
Project issues: github.com/Ytosko/Nutrino/issues