Privacy, written in plain ink.

01At a glance

This table is the whole policy in one page. The sections below add the legal detail, not a different answer.

02Who we are

Dearvell is operated by Zero Soleil (“Zero Soleil”, “we”, “us”), an independent software studio based in India. Zero Soleil is the developer and data controller responsible for the Dearvell Android application, package com.zerosoleil.dearvell, and this website, dearvell.zerosoleil.com. Our studio sites are zerosoleil.com and zerosoleil.in.

For any privacy question, request, or complaint, write to support@zerosoleil.com. We are the same entity that publishes Dearvell on Google Play and that registered the OAuth client requesting drive.appdata.

03Your phone first

Dearvell is offline-first by design. When you write a page, the page is saved to an encrypted local database on your device using SQLite with Drift and SQLCipher. You can open your journal, read old entries, and write new ones in airplane mode. No connection is required to reach your own words.

The local vault is protected by your device’s hardware-backed keystore and, when enabled, a biometric gate. Media files such as photos and voice memos are encrypted on disk before they are written. Deleting the app normally deletes its local sandbox, but use the in-app delete control if you want to be certain the vault is wiped before uninstalling.

04Google Drive, narrowly

If you connect Google Drive for backup, Dearvell requests exactly one sensitive OAuth scope: https://www.googleapis.com/auth/drive.appdata. This is the application data folder scope. It does not grant access to the rest of your Google Drive.

Dearvell uses that scope only to create, list, download, and delete its own hidden backup archive inside the app’s appDataFolder. Dearvell never reads, opens, indexes, modifies, or deletes your personal Drive files, photos, documents, email, or files created by other apps. The backup is not visible in the normal Google Drive interface, and other apps cannot browse it.

• No sale or advertising: Google user data is never sold, rented, or shared with advertisers, data brokers, or other third parties.
• No AI training: Google user data and your journal content are never used to train, fine-tune, or improve AI models.
• No routine human reading: Zero Soleil staff do not read your journal as part of normal operations. Access to account metadata is limited to support and security staff who need it to operate the service.
• Limited Use: Our use of information received from Google APIs is limited to providing and improving the backup feature you asked for, as permitted by the Limited Use requirements.
• Revocation: You can disconnect Dearvell at myaccount.google.com/permissions. Revoking access stops future access; it does not by itself erase the hidden archive. Use the in-app cloud-vault deletion described below.

05Encryption & key escrow

Your backup archive is encrypted on your device with a random 256-bit Data Encryption Key (DEK) using AES-256-GCM. The encrypted archive is then uploaded to your hidden appDataFolder. Google Drive stores ciphertext, not readable journal pages.

To restore on a new device, the DEK has to survive the old phone. Dearvell therefore wraps the DEK on the server using a Master Key Encryption Key (Master KEK) and stores only the wrapped ciphertext and nonce. The wrapped key is bound strictly to your authenticated backup_drive_email. When you restore, the server unwraps the DEK and returns it over TLS only to an authenticated session whose Google email matches that bound address. The app compares the signed-in Google email with the bound address before any Drive upload or download; a mismatch returns BACKUP_ACCOUNT_MISMATCH and nothing is read or written.

Zero Soleil does not store your journal prose, titles, photos, or voice memos on its servers, and does not use your Google credentials to browse your Drive. Drive calls happen on your device under the drive.appdata scope.

06Account data

When you sign in, we receive and store the minimum needed to operate your account: your Dearvell user ID, email address, Google OAuth subject identifier, display name if provided, app preferences (shelf finish, default ink, theme), subscription status and purchase token status from Google Play, signed entitlement lease metadata, and the wrapped backup DEK described above. If you use email sign-in instead of Google, we store the email address and authentication credential data needed to secure the account.

We use this data to authenticate you, restore purchases, issue offline leases, provide backup and restore, prevent abuse, and respond to support requests. Depending on your jurisdiction, the legal bases are performance of our contract with you, our legitimate interests in securing and operating the service, compliance with law, and consent where consent is specifically required. We do not build advertising profiles.

07Telemetry & crash reports

Dearvell uses Firebase Analytics and Firebase Crashlytics, provided by Google LLC, to understand stability and to schedule quiet study reminders. The analytics event study_session_segment contains only: the session mode (write, read, or shelf_browse), the local hour of day, and the duration of the segment. Crash reports contain device model, operating-system version, app version, and a technical stack trace.

We never collect journal prose, page titles, search queries, photos, voice memos, keystrokes, or the contents of your vault through analytics or crash reporting. These signals cannot reconstruct an entry. Their purpose is limited to improving stability and choosing a quiet hour for study reminders. Session data may be processed by Google as our service provider under its data processing terms and retained according to our Firebase retention settings. Where the app offers an analytics preference in Sanctuary Settings, turning it off stops future session events.

08AI & your words

Dearvell does not use your journal prose, titles, photos, or voice memos to train AI models, and does not sell them to anyone who might. Optional cloud-assisted features are off unless you choose them, and are scoped to the specific request you make. Content sent for an optional AI feature is processed in volatile memory to return the result to you, is not used for model training, and is not retained as a permanent corpus. Core journaling, reading, search, and backup do not require AI features.

09Processors & sharing

We use a small set of service providers to run Dearvell. They may process data only on our instructions and for the purposes described here:

• Google Sign-In and Google Drive — authentication and your hidden appDataFolder backup vault.
• Google Play Billing — purchase, renewal, refund, and subscription-status processing. Zero Soleil does not receive your full payment card details.
• Firebase Analytics and Crashlytics — anonymous session segments and technical crash diagnostics.
• Our hosting and database providers — account rows, entitlement metadata, and wrapped key material, under access controls and encryption in transit.

We may disclose data if required by law, to protect a person’s safety, to investigate abuse, or to enforce our Terms. We do not sell personal data, share it with ad networks, or use Google user data for personalized advertising. If Zero Soleil is involved in a merger or acquisition, account data may transfer subject to this policy and applicable law; we will notify you before a different policy applies.

10Retention & deletion

Local vault data stays on your phone until you delete it. The hidden Drive archive stays in your Google account until you delete it. Account rows, subscription records, and the wrapped DEK stay on our servers while your account is active or as needed for legal, tax, and fraud-prevention obligations.

Delete the local vault

Open Dearvell → Sanctuary Settings → Vault & Data → Delete local vault. This wipes the encrypted database and local media. Uninstalling the app also removes its local sandbox on Android, but the in-app control is the explicit route.

Delete the Google Drive backup

Open Dearvell → Sanctuary Settings → Vault & Data → Delete cloud vault. This deletes Dearvell’s archive from its appDataFolder. You can also revoke Dearvell’s access at Google Account permissions, though revocation alone may leave the hidden archive in place. The archive is not visible in the regular Drive file list by design.

Delete your Dearvell account and escrowed key

Email support@zerosoleil.com from the email connected to your account with the subject “Dearvell account deletion”. After verifying control of the account, we delete the account row, wrapped DEK, preferences, and associated non-financial metadata, and we confirm by reply. We aim to complete verified requests within 30 days. We may retain minimal purchase or tax records where law requires, and security logs for a limited period to prevent abuse. Deleting your account does not automatically delete the hidden Drive archive; use the Cloud vault control first, or ask us to walk you through it.

11Security & your rights

We use TLS in transit, AES-256-GCM for backup archives, wrapped-key storage with access controls, hardware-backed local key storage, biometric app locking where available, and least-privilege server access. No system is perfectly secure. If you discover a vulnerability, please contact us privately at support@zerosoleil.com before disclosing it publicly.

Subject to applicable law, you may request access to, correction of, or deletion of your personal data; object to or restrict certain processing; withdraw consent; request portability of data you provided; and lodge a complaint with a supervisory authority. If you are in India, you may raise a grievance with our support contact and, where applicable, the Data Protection Board of India under the Digital Personal Data Protection Act, 2023. If you are in the EEA or UK, you may contact your local supervisory authority. We do not discriminate against you for exercising these rights.

Dearvell is not directed to children under 13 (or under 16 where local law requires a higher age of digital consent). We do not knowingly collect personal data from children. If you believe a child has created an account, contact us and we will delete it.

We may update this policy to reflect changes in the app or the law. We will post the new version here with a new effective date and, for material changes, notify you in the app before they take effect.

12Contact

Zero Soleil — developer of Dearvell
Website: dearvell.zerosoleil.com
Email: support@zerosoleil.com
Studio: zerosoleil.com · zerosoleil.in
App: com.zerosoleil.dearvell on Google Play

This privacy policy is effective 29 October 2026. It applies to the Dearvell Android application and the marketing site at dearvell.zerosoleil.com. For contractual terms, see Terms of Service.