Private by design

Your wallet.
Your device.

stack keeps card details encrypted locally on your Android device. This page explains exactly what leaves your phone, how to delete your account, and how to reach us.

Read privacy policy Delete an account
stackLocal card wallet
••••  ••••  ••••  4821
STORED ONThis device
✓
Encrypted locallyAES-GCM + Android Keystore
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No card cloud syncCard data never reaches our server
Local firstCards and CVVs stay on-device
EncryptedProtected by Android Keystore
TransparentClear account and data controls

Effective June 11, 2026

Privacy Policy

Plain language about what stack stores and why.

01

Card information stays local

Card information you enter, including bank name, cardholder name, card number, expiry date, CVV, network, card type, and appearance, is stored only within stack on your Android device.

The vault is encrypted with AES-GCM using a key protected by Android Keystore. stack does not upload card information to Firebase, our servers, cloud backup, analytics, or advertising services.

02

Account information

If you sign in, Firebase Authentication processes information required by your chosen sign-in method:

  • Google: account identifier, email address, and display name.
  • Email: email address, authentication identifier, and display name.
  • Phone: phone number and authentication identifier.

Passwords and SMS verification codes are handled by Firebase Authentication and are not stored by stack.

03

Purchases and subscriptions

Google Play processes premium purchases and may process payment method, transaction, country, tax, and billing information under Google's privacy terms. stack receives purchase status and product information needed to unlock premium access. We never receive your full payment-card details.

04

Retention and deletion

  • Local card data remains until you delete it, clear app storage, or uninstall stack.
  • Firebase account information remains until your account is deleted.
  • Google Play retains purchase records under its billing and legal requirements.
  • Support messages are kept only as long as needed to resolve requests or meet legal obligations.

Signing out does not delete cards because cards belong to the local device vault, not the online account.

05

Security and contact

stack uses Android Keystore-backed encryption, device authentication for sensitive actions, screen protection in release builds, encrypted local preferences, clipboard clearing, and disabled cloud backup for the card vault.

No security method can guarantee absolute protection, particularly on rooted or compromised devices. stack is not directed to children under 13.

Privacy questions can be sent to yoursupportstack@gmail.com.

Your account, your control

Delete your account

Delete directly inside stack or prepare a request if you cannot access the app.

Recommended

Delete inside the app

  1. 1

    Open stack and complete device authentication.

  2. 2

    Open Settings and select your account.

  3. 3

    Select Delete account.

  4. 4

    Choose whether to keep or delete local cards.

  5. 5

    Confirm using your phone's security screen.

Local cards are separate. Deleting your online account cannot remotely erase cards on another device.
Cannot access the app?

Prepare a deletion request

Send a deletion request to stack support. We may verify account ownership before deletion.

✓

DeletedFirebase authentication identity and associated profile information.

⌁

Local onlyCards remain inaccessible to stack and must be removed from the device.

i

May be retainedGoogle Play transaction records and legally required support correspondence.

Here when you need us

Support

Account, subscription, sign-in, and app help from a real inbox.

@
Email supportyoursupportstack@gmail.comOpen your mail app
✓

Keep sensitive details private

Never send full card numbers, CVVs, passwords, verification codes, or phone screen-lock credentials. stack support will never ask for them.

Are my cards backed up?+

No. Cards remain encrypted on the Android device and do not transfer automatically to a new phone.

What happens when I sign out?+

Your cards remain locally stored. Signing out removes the active account session, not the device vault.

How do I delete everything?+

Open Settings, select your account, choose Delete account, then choose Delete account and all cards.

Who handles payments and refunds?+

Google Play processes purchases, manages payment methods, and handles applicable refund workflows.