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/Neutrino 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 (through 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), OpenAI, Groq or OpenRouter. 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
• Groq: console.groq.com/docs/your-data (by default Groq doesn't keep requests; it may keep them for up to 30 days to investigate problems or abuse, which you can turn off in its Data Controls)
• OpenRouter: openrouter.ai/privacy. OpenRouter passes the request to the company that runs the model you picked. Some free models come from providers that may use requests to improve their models; you choose which are allowed in your OpenRouter privacy settings. Neutrino uses OpenRouter for photos only, not for voice, and tells OpenRouter the requests come from "Neutrino".
• 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, the name of a new food you add, or what you say to the voice assistant (below) is sent with the instructions, together with the optional cuisine and notes you set in the app.

Voice (optional)

Voice is off until you turn it on in AI models and set up a voice model with your own API key. Then you can log meals, water, blood glucose and medicines by speaking, and change a meal on its review page.

• Microphone: Neutrino asks for the microphone permission the first time you tap the mic, and listens only while you tap or hold it. It never listens in the background.
• The recording is kept in memory only, sent once to your voice model's provider (Google, OpenAI or Groq) to write down what you said, and then discarded. It is never saved to your device's storage.
• The written-down words are sent to your Primary model (and its fallbacks, if it fails) to work out what to log. On a review page, the foods and amounts on that page go with it, so the assistant can change them, together with the last few things you said about that meal and what they changed, so it can follow a conversation ("no, I said three"). That conversation is kept only in memory and forgotten when you save the meal or leave the page. If you keep a medicine log, your medicine list (names, strengths and generic names) goes with it too, so the assistant picks exactly the medicine you mean; with the medicine log off, it is not sent.
• Glucose and medicine: if you say a blood glucose value or a medicine, those words reach the providers above like everything else you say. A glucose reading is only saved after you confirm it on screen, and replies never read glucose values aloud.
• Spoken replies use your phone's own text-to-speech engine, and no other service. You can turn them off; they're also shown as text when your phone is silent.

Open Food Facts

When you search for a food and type three or more letters, Neutrino also searches Open Food Facts, a free, open database of packaged products, so you can log branded items. Only the search text is sent, along with the app's name and version, which Open Food Facts asks apps to identify themselves with. Open Food Facts' own privacy policy applies to those requests. Built-in foods and your own food list are searched on your device without any network request.

Ramadan times (optional)

If you turn on Ramadan mode, Neutrino asks Ummah API (a free prayer-times service) for that year's Ramadan dates and each day's Sehri and Iftar times, for a city you choose or, if you turn on Use my location, for where your phone is. Only the coordinates (a listed city's, or your approximate location rounded to about 10 km), the time zone, the calculation method and the year are sent; no account, meals or health data. The schedule is kept on your device and fetched again only for a new place or a new year.

Use my location asks for Android's approximate location permission and checks it only while Neutrino is open: when you open the app or the Meals and reminders page, and every hour while it stays open. Neutrino never reads your location in the background, keeps only the rounded place, and sends it nowhere except Ummah API as described. Turn the switch off, or pick a city, to stop using location.

Daily goals and goal suggestions (optional)

In Daily goals you can enter your age, sex, height, current and target weight, a plan length, your regular workouts, and health conditions (diabetes with your average blood sugar, high blood pressure with your usual reading, thyroid with your TSH, FT3 and FT4). All of this is kept on your device only.

If you tap Recalculate my intakes and then Analyse, Neutrino sends these details, the names, doses and times of the medicines in My medicines, and your meter's 30-day average blood sugar (if you have diabetes on and didn't type your own) to the AI provider you set up, to suggest daily calories, carbohydrates, protein, fat and water. The provider's own privacy terms apply, as for meal photos. Nothing is sent unless you tap Analyse, and the suggestion changes your goals only when you confirm it.

The weekly weigh-in reminder (Monday morning unless you change it) is a notification on your device; the weight you enter is saved on your device and, if you allow it, written to Health Connect.

Bluetooth glucose meter (optional)

If you pair a Bluetooth blood glucose meter (for example a CONTOUR PLUS ELITE), Neutrino downloads new readings from it after each test and saves them on your device. Blood glucose is sensitive health data, so Neutrino handles it with extra care:

• Direct from the meter: readings travel over Bluetooth from your meter to your phone. They never pass through any server.
• Where they go: kept in the app on your device, written to Health Connect if you allow it, and included in your encrypted backups. They are never sent to AI providers, Open Food Facts or the Neutrino project.
• Permissions: Neutrino asks for Android's "Nearby devices" permission to find, pair with and connect to your meter, and to notice it in the background after a test. It is declared so that it is never used to work out your location, and Neutrino does not request location access.
• Background syncing: Android wakes Neutrino when your paired meter is nearby after a test, even if the app is closed. Neutrino connects only to glucose meters, and only to the ones you paired (up to five).
• Meter clock: to keep reading times correct, Neutrino may set your meter's clock to your phone's time when the meter allows it.
• Notifications: the "new readings" notification shows only how many readings were saved, never their values, and is hidden on the lock screen. The optional weekly summary is also hidden on the lock screen, and the optional "time to test" reminder contains no values.
• Home screen widget: if you add Neutrino's widget, it shows today's totals and your latest glucose reading on your home screen, where anyone who sees your screen can see it. You can hide the reading in Settings.
• Not medical advice: Neutrino shows readings exactly as your meter measured them. It is not a medical device and gives no diagnosis or treatment advice.
• Stopping: open the meter in Settings → Glucose meters and choose "Forget meter". Readings already saved stay until you delete them in the app.

Reports, exports and app lock

• Doctor report and data export: the PDF report and the CSV export are made on your device. Neutrino never uploads them; they only go where you choose to share or save them, and the copy Neutrino made is replaced the next time you export.
• App lock: uses your phone's own fingerprint, face or screen lock through Android. Neutrino never receives or stores your fingerprint, face or PIN.
• Hide in recent apps: when on, Android blanks Neutrino's preview in the app switcher and blocks screenshots of the app.

Blood glucose from other apps (optional)

If you turn on Import from other glucose apps in Settings, Neutrino asks Health Connect for permission to read blood glucose, and nothing else. It then brings in readings that other apps (for example continuous glucose monitor apps such as xDrip+ or Juggluco) saved to Health Connect, whenever you open Neutrino. Readings are kept on your device so they can appear in your charts and next to your meals. They are not written back to Health Connect and are never sent anywhere else. Turn the setting off, or remove the permission in Health Connect, to stop.

Medicines and insulin (optional)

If you turn on I take medicine or I use insulin in Settings, you can keep a list of what you take, log doses and get reminders at times you choose. This stays on your device and in your encrypted backups; reminders are scheduled by your device. On the lock screen a reminder only says "Medicine reminder". Neutrino only records what you enter; it never suggests or calculates a dose.

While you add a medicine, Neutrino can suggest names from MedEx, a Bangladeshi medicine index: after you type three or more letters, that text is sent to MedEx, and when you pick a suggestion, its MedEx page is fetched to fill in the medicine's group (generic name). Nothing else is sent. MedEx's own terms and privacy policy apply to those requests. You can always type a name yourself instead.

Wear OS watch (optional)

If you install the Neutrino watch app, the phone app sends today's totals, water and latest glucose reading to your own paired watch through Google Play services' Wearable Data Layer, and the watch can ask the phone to add a glass of water. This data only travels between your phone and your watch.

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.
• Write blood glucose: to save your meter's readings and readings you type in, with the time and meal mark.
• Write weight: to save the weight you enter in Daily goals (for example at the weekly weigh-in).
• Read blood glucose (only if you turn on glucose import): to bring in readings other apps saved, as described above.

Apart from blood glucose when you turn on import, Neutrino does not read any health data from Health Connect, such as heart rate, sleep or activity. 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: one backup file containing your settings (including your AI API key), meal history with small meal photos, water log, blood glucose readings, medicines and doses (if you log them) and personal food list. The same encrypted file is also kept in a hidden folder on your device.
• 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”. Each upload replaces the previous one.
• 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. Disconnecting stops uploads and removes Neutrino's access. To delete the stored backup, open Google Drive on the web, go to Settings → Manage apps → Neutrino and choose 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. The Bluetooth permission used for a glucose meter is declared as not used for location.
• 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: kept in a hidden folder in your device's shared storage so it survives reinstalling Neutrino. It stays until you delete it or reset the device. To save it there, Neutrino asks for Android's "All files access"; it uses that access only for its own backup file.
• 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/Neutrino/issues