Billnix Privacy Policy

Overview

Blue Sparrow is a solo developer based in India and operates Billnix, a recurring bills and subscriptions tracker. This policy explains what Billnix and its connected services handle, why the information is needed and the choices available to you. Billnix is designed around data minimisation, purpose limitation, transparency and rights principles supported by the EU General Data Protection Regulation and other applicable privacy requirements.

Billnix requires Google sign-in for the normal app flow. It saves a working copy to an app-private device database and synchronizes supported account records through the Billnix backend. Optional reminders, Google Drive backup, Premium purchases, provider logos, exports and support use the connections described below. Billnix does not sell personal information, display targeted advertising, connect to your bank or scan your inbox.

Data we handle

Depending on what you enter or enable, Billnix may handle:

• Google and Firebase identity details such as user identifier, email, display name, profile-photo URL, sign-in provider and authentication timestamps.
• Recurring-commitment details such as provider and plan, account email or phone, amount, currency, billing interval, renewal, trial, access and cancel-by dates, timezone, lifecycle status, category, manage and cancellation links, provider support contacts, cancellation notes, payment-method label, personal notes, icons and colours.
• Reminder and preference information such as offsets, channels, quiet hours, notification-content choice, default currency, timezone, appearance, email digest selection and email or Telegram opt-in state.
• Device and synchronization information such as generated device identifier, platform, app version, push-permission state, Firebase Cloud Messaging token, sync cursors, pending mutations, error state, request identifiers and operational timestamps.
• Email and Telegram delivery information such as the signed-in email address, Telegram chat endpoint and link status, message fields needed for the reminder, delivery state, provider message identifier and error details.
• Google Drive backup information such as checkpoint identifiers, compatibility data, manifests, indexes and readable database snapshots stored in the hidden app-data area of the Google account you authorize.
• Google Play and RevenueCat information such as app-user identifier, email, display name, product, transaction, trial, renewal, cancellation, receipt and entitlement state. Blue Sparrow does not receive your full payment-card details.
• Export information in JSON, CSV or support-package files generated on the device, including the records and diagnostics shown in the export preview.
• Support or feedback information you submit, including reply email, optional name and topic, message, app version, platform and locale. The attested support form does not attach the separate diagnostics package automatically.
• Service logs and security records such as request timing, response status, redacted or protected identifiers, abuse signals, entitlement delivery receipts and account-deletion markers.

Billnix does not need precise location, contacts, SMS, call history, microphone recordings, health records, government identifiers, bank credentials, full payment-card numbers or advertising identifiers for its current workflow. Avoid entering unnecessary secrets in notes, labels or contact fields.

How we use data

Information is used only as reasonably necessary to:

• Authenticate the account and associate local, synchronized, reminder and purchase state with the intended user.
• Create, organize, search, display, synchronize and recover recurring-commitment records.
• Calculate upcoming dates, lifecycle context, totals and insights from the information you provide.
• Schedule and deliver local push, optional email and optional Telegram reminders.
• Create, list, restore and delete optional Google Drive checkpoints.
• Validate purchases, restore Premium access and enforce feature limits.
• Generate exports on the device and show existing export files.
• Receive and answer support or feedback you choose to submit.
• Operate, secure, diagnose and maintain the app, API, workers and delivery infrastructure.

Billnix does not use your records to build advertising audiences or sell or rent them to others.

Storage and synchronization

The working device database is an ordinary SQLite file in app-private storage. It is not application-level encrypted. Android platform backup is disabled, but device compromise or storage extracted outside normal protections can expose readable records. The database remains the immediate source used by the interface and writes changes locally before supported network synchronization.

The Billnix backend stores account, subscription, category, settings, reminder, device, sync and entitlement data in PostgreSQL for same-account continuity and server-owned reminders. The audited schema encrypts Firebase Cloud Messaging tokens at rest, but other application fields are not described as end-to-end encrypted. Blue Sparrow can process synchronized records when reasonably necessary to provide and support the service.

Synchronization is not a zero-knowledge service. A sign-out flow clears the current user's local records and artifacts on that device, while server data remains available to the same account unless the account-deletion flow or a verified privacy request removes it.

Reminders and communications

Local notifications use the notification permission you grant and can be recreated after device restart. You can hide sensitive notification content and change or disable local rules.

Email delivery can use the signed-in Google email, provider name, amount, currency, dates and links needed for the message. A one-time setup summary sends only when requested. Eligible Free accounts can receive a weekly digest and a limited introductory transactional-email period; Premium can enable ongoing transactional email and a daily digest where available.

Telegram reminders require an explicit bot-link flow. The backend stores the Telegram endpoint and link state and sends relevant reminder content to Telegram when enabled. Disconnecting the channel stops future use through Billnix, but Telegram and recipients can retain delivered messages under their own controls.

Backups and exports

Google Drive backup is optional and uses the hidden app-data scope rather than access to general visible Drive files. The app creates JSON data, compresses it and wraps it in base64 with integrity hashes before upload. This is encoding and integrity protection, not encryption. The root index and manifest are also readable data. Anyone who gains suitable access to these files can potentially read account and subscription content.

Drive backup is an explicit checkpoint-and-restore layer, not live synchronization. The mobile app connects directly to Google Drive; the Billnix backend does not receive the Drive file contents. Restore checks account boundaries and integrity values, but no recovery system can guarantee preservation.

Premium can create ordinary JSON, CSV and support-package files in Downloads or app documents. These files are not encrypted by Billnix and can include contact details, notes, URLs, amounts, dates and diagnostics. Existing exports can remain after downgrade, sign-out or account deletion if they were placed outside the app-private area. The destination, recipient and any later copy control their own retention.

Providers and disclosures

Blue Sparrow does not disclose Billnix records for independent advertising. Limited information may be processed by:

• Google and Firebase for Google sign-in, Firebase Authentication, App Check, Firebase Cloud Messaging, Google Drive and Google Play.
• RevenueCat and Blue Sparrow's subscription gateway for product configuration, purchase validation, entitlement state, webhook delivery and related receipts.
• Blue Sparrow's Billnix API, PostgreSQL database and reminder workers for synchronization, entitlements and notification delivery.
• Blue Sparrow's mail infrastructure for setup, digest, transactional and support messages.
• Telegram when you link the bot and enable its reminder channel.
• Blue Sparrow's attested support-request service and delivery infrastructure when you submit a support or feedback form.
• Logo.dev when a build contains its publishable key and a known provider lacks an included icon. The app can request a logo using a known provider name or a domain derived from a manage or cancellation URL; Logo.dev also receives ordinary connection metadata such as IP address. Custom free-typed provider names without a known template are not sent for name lookup.
• The operating system and any file destination or recipient you choose for an export.

These third-party providers operate under their own notices, retention practices and infrastructure. Blue Sparrow may also make a limited disclosure when required by applicable rules or reasonably needed to address fraud, abuse or a serious security threat.

Retention and deletion

Active synchronized records remain while needed to provide the account until you archive or delete individual records, complete account deletion or make an applicable request. Soft-deleted records, synchronization changes, mutation receipts, reminder jobs, delivery attempts, Telegram setup tokens, purchase-delivery receipts, security logs and deletion markers can remain for operational integrity, retry, abuse prevention and provider requirements. The audited backend does not establish a universal automatic expiry for every table, so Billnix does not promise a fixed deletion schedule for all operational records.

The in-app account-deletion flow reauthenticates with Google, then attempts server deletion, optional Drive cleanup, local cleanup and Firebase Authentication deletion in that order. A required failure stops later destructive steps so you can retry. Server deletion removes the main user row and cascades account-scoped application tables, while a limited Firebase-UID deletion marker remains to prevent accidental account recreation. The current backend reports RevenueCat customer deletion as not configured, so purchase-provider records are not removed by this flow. Google Play cancellation is always separate.

Drive cleanup occurs only if selected and authorization is still available. Local cleanup removes app-scoped database rows, reminders, preferences, caches and app-created artifacts it can identify. Uninstalling, clearing app data, revoking Drive access, deleting an account or signing out does not retrieve exports, delivered messages, provider records or copies held by another destination.

Security

Billnix uses proportionate safeguards including HTTPS, Firebase Authentication, App Check for the support form, account-scoped API authorization, local-first writes, disabled Android backup, encrypted backend FCM tokens, service-level secrets and constrained support requests without a reusable client API key.

The local SQLite database, Drive snapshots and generated exports are not application-level encrypted. Email, Telegram and notification content can also be visible to the selected provider, device or recipient. Protect your device and Google account, use device-level security, avoid unnecessary secrets in Billnix and secure exported files. No device, transmission, provider or storage method can be guaranteed completely secure.

Your choices and rights

You can manage records, notification content, reminder rules, email and Telegram opt-ins, Telegram linking, Drive access, backups, exports, provider-logo attribution, purchases, sign-out and account deletion through the relevant app or provider controls.

Depending on where you live and subject to applicable exceptions, you may have rights to know or access personal information, correct it, receive a portable copy, delete it, restrict or object to processing, withdraw consent and contact a data-protection authority. These protections include, where applicable, the EU GDPR and EEA rules, UK GDPR, India's Digital Personal Data Protection framework, California and other US state privacy rules, Brazil's LGPD, Canada's privacy rules and comparable requirements elsewhere.

Email [email protected] with Billnix in the subject and enough detail to identify the relevant account or request. Blue Sparrow may ask for proportionate verification and will respond within the period required where you live.

Children

Billnix is a general recurring-commitment organizer and is not directed to children. A parent or guardian should supervise use by anyone who cannot validly make account, purchase, backup or communication choices. Do not add another person's contact information unless you have an appropriate reason and permission. Contact [email protected] if you believe a child's information was provided inappropriately.

International processing

Blue Sparrow-controlled synchronized content and operational backups are intended to remain in European Union infrastructure, subject to verified production-datacentre and offsite-backup evidence. This is not an unconditional location promise. Google sign-in, Firebase Authentication, App Check, Cloud Messaging, Google Drive, Google Play, RevenueCat, Logo.dev, email, Telegram and support delivery can process limited information in other regions. Blue Sparrow support access may occur from India.

Where transfer safeguards are required, Blue Sparrow and relevant providers rely on appropriate contractual, adequacy or other permitted mechanisms and apply data-minimisation and security measures. Connected provider metadata is not promised to remain exclusively in the European Union. EU users retain the protections required by the EU GDPR when a necessary provider connection crosses a regional boundary.

Changes

This policy may change when Billnix, its providers or applicable requirements change. Material updates will be presented in the app or at https://bluesparrow.dev where appropriate, and the updated date will be revised.

Contact

Blue Sparrow is the developer and privacy contact for Billnix. For privacy questions or rights requests, email [email protected]. For general help, email [email protected]. Product and policy information is available at https://bluesparrow.dev.