Mononote Privacy Policy

Effective date: 2026-10-15
Last updated: 2026-10-15

Mononote is a single-note app for Android, published by Oscillator Michał Dobrzański (“we”, “us”). This policy explains what Mononote does and does not do with your information. It covers the Android app com.oscillator.mononote and nothing else.

The short version

Your note stays on your phone. There is no account, no sign-up, and no server that holds your writing. The only information that ever leaves your device is your purchase history and an anonymous purchase identifier, and only from the moment you open the Pro screen. Until then the app makes no network requests at all.

Your notes

• Your active note and every archived note are stored only on your device.
• They are encrypted at rest with a key held in your phone's Android Keystore, hardware-backed on devices that support it. The key is not exportable: the app itself can never read it.
• They are excluded from Google cloud backup and from device-to-device transfer, because the encryption key cannot move between devices. If you change phone, use Export and Import inside the app to carry your notes across.
• We never receive your notes, so we cannot read them, hand them over, or recover them for you.
• Mononote is designed to display your note outside the app: on your lock screen, in the notification shade and in a home-screen widget. When you turn those on, Android's own system UI shows the text. Anyone who can see your screen can read it. “Hide note on lock screen” and the biometric app lock are there for when that is not what you want.
• Exporting or sharing a note sends it to whichever app you choose in the Android share sheet. That transfer is yours, not ours, and what the receiving app does with it is governed by that app's policy.

Purchases

Mononote Pro is a one-time purchase. If you buy it:

• Google Play Billing processes the payment. We never see your card details, name or address.
• RevenueCat, Inc. manages the purchase receipt so the app knows you own Pro, including after a reinstall or on a new phone. RevenueCat receives your purchase history (which product, when, the store's transaction identifiers, and your country and currency), and an anonymous app-user identifier that we generate. We do not send RevenueCat your name, your email address, your advertising identifier or your notes.
• Purpose: to deliver what you paid for (app functionality) and to understand aggregate purchase numbers (analytics). Legal basis in the EEA and the UK: performance of the contract you enter when you buy Pro.
• All of this data is encrypted in transit.

When the app contacts RevenueCat, and when it does not. The billing SDK is not started when the app launches; it is started the first time you open the Pro screen, tap Restore, or buy. That first request is also what registers the anonymous identifier, because the prices on the Pro screen come from the store. Once you own Pro the app re-checks the receipt when it comes to the foreground, so a refund or a cancelled purchase takes the unlock back; that check is the only network request Mononote ever makes on its own, and it is only made on a device that owns Pro. If you never open the Pro screen, Mononote transmits nothing at all.

What we do not collect

No name. No email address. No phone number. No account. No location, precise or approximate. No contacts, calendar, photos, files or messages. No advertising identifier, and no device identifier - the only identifier we ever generate is the anonymous purchase identifier described under Purchases. No analytics on how you use the app; the only figures we ever see are aggregate purchase counts, described there too. No crash reports or diagnostics. No ads and no advertising trackers, ever.

Mononote requests the notification permission only so it can show your note on your lock screen. That permission gives us nothing about you.

Sub-processors

Who	What they receive	Why	Their policy
Google LLC (Google Play Billing)	Payment and transaction data	To process the purchase	policies.google.com/privacy
RevenueCat, Inc.	Purchase history, anonymous app-user id	To manage and restore your Pro entitlement	revenuecat.com/privacy

Google's billing library brings Google's own diagnostics transport into the app. It is part of Google Play Billing, we send nothing through it, and it stays dormant until the billing library is started - which happens only when you open the Pro screen.

We add no other third party without updating this policy and the Play data-safety declaration first.

How long it is kept

• Notes: on your device, until you delete them or uninstall the app. Uninstalling removes them.
• Purchase records: kept by RevenueCat and Google for as long as the entitlement exists, and for as long as they are required to keep transaction records. Deleting them ends your ability to restore Pro without repurchasing.

Deleting your data

• Notes: delete them in the app, or uninstall Mononote. Nothing is left on a server, because nothing was ever sent to one.
• Purchase history: email dobrzanskioscillator@gmail.com from the address you would like us to act on, or use https://michaldanieldobrzanski.github.io/mononote/delete-my-data. We will ask Google Play for the order identifier needed to locate the record, delete the RevenueCat customer record, and confirm. Note that Google keeps its own transaction records independently of us, for tax and refund purposes.

Children

Mononote is not directed at children and we do not knowingly collect anything from a child. There is nothing in the app to sign up for and nothing to share with anyone.

Security, stated honestly

Encryption at rest means that a copy of your phone's storage, a stolen backup or a disk image cannot be read without the key, and the key never leaves the device. It does not protect against someone using your unlocked phone, against malware running with the app's own permissions, or against anyone who can see your lock screen or your home-screen widget. We do not claim end-to-end encryption, because there is no second end; there is no server.

Changes

If this policy changes, the effective date above changes with it, and a material change is announced in the app's release notes.

Contact

Oscillator Michał Dobrzański
ul. Św. Wincentego 110/65, 03-291 Warszawa, Poland
dobrzanskioscillator@gmail.com
michaldanieldobrzanski.github.io