Privacy Policy — The Stack

Last updated: 23 July 2026

Who we are

The Stack ("we", "us", "the app") is a personal care routine tracking application operated by Steady State Studios Pty Ltd (ABN 50 700 587 631), based in Melbourne, Australia. You can contact us at support@thestackapp.app.

This policy explains what personal information we collect, how we use it, how we store it, and the rights you have over it. We handle personal information in accordance with the Australian Privacy Act 1988 (Cth) and the Australian Privacy Principles (APPs). If you are in the European Economic Area or the UK, additional rights under the GDPR/UK GDPR may apply (see "International users").

What we collect

Account information. When you create an account we collect your email address and an authentication identifier from your chosen sign-in provider (email/password, Google, or Apple). We do not store your password — authentication is handled by Google Firebase Authentication.

Routine and profile data you enter. This is the core of the app and includes the products you use, your skincare/haircare/scent routines, completion history, journal notes, and any profile details you choose to provide during onboarding (for example, skin concerns, preferences, and free-text notes). Some of this may constitute health-related information or sensitive information under the Privacy Act. We collect it only because you choose to enter it, and only to provide the app's features to you.

AI assistant interactions. If you use the AI assistant ("Facet"), the messages you send, relevant routine context, and recent journal entries are transmitted to our processing service to generate a response (see "Third parties" below). Photos you submit for analysis are processed to produce a text description and are not retained as images — only the resulting text analysis is stored in your account.

Technical data. Basic technical information necessary to operate the service (for example, error logs). We do not use advertising trackers, and the app is ad-free.

How we use your information

We use your information to: provide and operate the app's features; sync your data across your devices; generate AI assistant responses when you use that feature; maintain and improve reliability and security; and communicate with you about your account (for example, password resets).

We do not sell your personal information, and we do not use it for advertising.

Where your data is stored

Your account and routine data are stored in Google Firebase (Firestore), in the australia-southeast2 (Melbourne) region. Authentication is handled by Firebase Authentication. Data may be cached locally on your device to allow offline use.

Third parties we share data with

We share data only with service providers that help us run the app, and only as needed:

• Google Firebase (Authentication and Firestore database) — stores your account and routine data.
• Anthropic — processes AI assistant messages and context to generate responses, via our server. See Anthropic's privacy policy for how they handle data submitted through their API.
• [Payment provider — to be confirmed once subscriptions launch, e.g. Stripe / Apple / Google] — if you purchase a subscription, processes your payment. We do not store your full payment card details.

Each provider handles data under its own terms. We do not authorise them to use your data for their own purposes beyond providing the service to us, to the extent we can control this.

Health and sensitive information

Some data you enter may be sensitive or health-related. We collect it only with your consent (by you choosing to enter it), use it only to provide the app's features, and never disclose it for marketing. You can delete this information at any time (see "Your rights").

The Stack is not a medical device and does not provide medical advice. See our separate Medical Disclaimer.

Your rights

You can:

• Access the personal information we hold about you.
• Export your data — the app provides an in-app export of your stored data at any time.
• Correct information that is inaccurate — most data is directly editable in the app.
• Delete your account and associated data — see "Account deletion" below.
• Withdraw consent by ceasing to use a feature and deleting the associated data.

To exercise any right, contact support@thestackapp.app. We aim to respond within 30 days.

Account deletion

Account deletion is currently handled by emailing support@thestackapp.app and requesting deletion — an in-app deletion option is planned but not yet available. Once processed, deletion removes your routine data, journal, profile, and AI memory from our active database. Backup snapshots are purged within 30 days. Some records may be retained where required by law.

Data retention

We keep your data for as long as your account is active. If you delete your account, we delete your data as described above. Local device caches are cleared when you sign out or delete the app.

Security

We use industry-standard measures to protect your data, including encrypted transport (HTTPS), authentication, and database access rules that restrict each user's data to that user. No system is perfectly secure; we cannot guarantee absolute security.

Children

The Stack is not directed at children under 13, and we do not knowingly collect their personal information. If you believe a child has provided us data, contact us and we will delete it.

International users

If you access the app from outside Australia, your data will be stored and processed as described above (including in Australia). If you are in the EEA or UK, you have additional rights under the GDPR/UK GDPR, including rights to restriction and portability, and the right to lodge a complaint with your local supervisory authority. Our lawful basis for processing is your consent and the performance of our service to you.

Changes to this policy

We may update this policy. We will post the updated version with a new "Last updated" date and, for material changes, notify you in-app or by email.

Complaints

If you have a privacy concern, contact us first at support@thestackapp.app. If you are not satisfied, you may contact the Office of the Australian Information Commissioner (OAIC) at oaic.gov.au.