Privacy Policy

Last updated: October 5, 2026

This Privacy Policy explains how the Android app Expense Tracker (package com.pahntd.expensetracker, "the app") collects, uses, stores and deletes your information.

1. Who we are

The app is developed and published by Pahntd. For any privacy question or request, contact pdtrong265@gmail.com.

2. Information we collect

a) Account information (required to use the app)

• Email address — used as your login and to identify your account.
• Password — sent over an encrypted connection when you register or log in. We store only a one-way hashed version (BCrypt); we never store your password in readable form.
• User ID — a random identifier created by our server when you register.
• Account timestamps — when your account was created and last updated.

b) Financial records you enter

• Transactions: amount, type (income or expense), category, date and an optional note you write.
• Categories: default categories created for you at registration and any custom categories you create (name and icon).

This information is entered manually by you. The app does not connect to banks, cards or payment services and does not process payments.

c) Authentication and session data

After you log in, our server issues a short-lived access token and a refresh token. The refresh token is stored on our server (with its creation, expiry and revocation time) so we can keep you signed in and sign you out. On your device, both tokens and your user ID are stored encrypted.

d) Security data processed temporarily

To protect accounts against abuse (for example, repeated login attempts), our server counts recent requests by IP address and login attempts by email address. These counters are kept for about 60 seconds and are not used for any other purpose.

e) Data collected by advertising services

See Section 6.

We do not collect your name, phone number, postal address, precise location, contacts, photos, files or messages.

3. How we use information

• To create and manage your account and let you log in and out.
• To store and synchronize your transactions and categories between your device and your account, so you can use them after reinstalling the app or on another device.
• To keep the service secure and prevent abuse (rate limiting of login, registration and token refresh).
• To show ads and to let you unlock certain statistics features by watching a rewarded ad (Section 6).

We do not sell your personal information and do not use your financial records for advertising.

4. Data stored on your device

The app is offline-first. A copy of your transactions and categories is stored in a local database on your device so the app works without a connection; changes are synchronized with our server in the background when you are online. The app also stores on your device: your encrypted session, the part of your email address before "@" (used for the greeting on the Home screen), and app settings (dark mode, statistics filter, temporary feature unlocks).

App data is excluded from Android backup and device-to-device transfer. When you log out or delete your account, the app removes your local transactions, categories, session and account-related settings from the device. Uninstalling the app also removes all local data.

5. Data stored on our server

Your account information and financial records are stored on our backend server, hosted by Render (Singapore region). The server is used only to operate the app. We do not share this data with other parties, except the hosting provider that stores it on our behalf.

6. Advertising (Google AdMob)

The app shows ads (a banner on the Statistics screen and optional rewarded ads) using the Google Mobile Ads SDK provided by Google. Before ads are requested, the app uses Google's User Messaging Platform to ask for your consent where required by law (for example in the EEA, the UK and Switzerland). You can change your choice at any time from Settings → Privacy options when this option is shown.

The Google Mobile Ads SDK may collect and process information such as your device's advertising ID and other device identifiers, your IP address (which can be used to estimate approximate location), interactions with ads, and diagnostic information, for advertising, analytics and fraud prevention. Ads are limited to content suitable for a general audience.

This data is collected by Google, not by our server. Learn more in Google's How Google uses information from sites or apps that use our services and the Google Privacy Policy. You can reset or delete your advertising ID in your device settings.

7. Sharing

We do not sell or rent your personal information. Information is shared only:

• with our hosting provider, which stores the backend data on our behalf;
• with Google, through the Google Mobile Ads SDK and User Messaging Platform, as described in Section 6;
• if required by law.

8. Security

• All communication between the app and our server uses HTTPS; unencrypted connections are blocked in the release app.
• Passwords are stored only as BCrypt hashes.
• Session tokens on your device are encrypted with keys protected by the Android Keystore.
• Each request to the server is authenticated, and every server query is limited to the data of the signed-in account.
• Repeated login, registration and token-refresh attempts are rate limited.

No method of storage or transmission is completely secure, and we cannot guarantee absolute security.

9. Data retention

• Account information and financial records are kept on our server until you delete your account. Transactions or categories you delete in the app are removed from the server at the next sync.
• Refresh tokens expire 30 days after login; token records are deleted together with your account.
• Rate-limiting counters (IP address, email address) are kept for about 60 seconds.
• We do not keep separate backups of your data.
• Our hosting provider may keep technical server logs for a limited time under its own policies. Our server does not write your email address, password or financial records to its logs.

10. Deleting your account and data

You can delete your account in the app (Settings → Delete Account) or by email, without the app. This permanently deletes your account (email, password hash, user ID), all of your transactions, all of your categories and all of your sign-in tokens. Full instructions: Delete your account.

Data collected by Google through the advertising SDK is managed by Google under its own policies (Section 6).

11. Children

The app is not directed to children and is intended for users aged 18 and over. We do not knowingly collect personal information from children. If you believe a child has created an account, contact us and we will delete it.

12. Changes to this policy

We may update this policy. The "Last updated" date above shows the latest version. Significant changes will be announced in the app or on its Google Play page.

13. Contact

Questions or privacy requests: pdtrong265@gmail.com