Privacy Policy

Kai Rickert (SignalByteStudio)
Sternbergstraße 10
76131 Karlsruhe
Germany
Email: signalbytestudio@gmx.de

Budget Book stores your entries on your device. I do not run a server for the app and have no access to your entries. The app has no user account, shows no ads and contains no analytics or tracking tools that I could use to analyse how you use it; for the log data of Google's billing library, see section 4.2.

Data leaves your device in these cases:

• → When you want to buy Premium or restore purchases, the app connects to Google Play, and afterwards also at start-up while Premium is active or if you started a purchase in the last 4 days (section 4).
• → When you rate the app, you submit the rating directly to Google Play (section 5).
• → When Android backup is switched on on your device, Android backs up the app's data to your Google account (section 6).
• → When you have agreed to share usage and diagnostics data with Google, Android sends information about crashes and the app's performance to Google (section 7).
• → When you use a photo backup (for example Google Photos), it also backs up receipt photos in your gallery (section 3.3).
• → When you pass something on yourself: an export file, a receipt photo from your gallery, a text via "Share with Friends" or an email to me (sections 3 and 9).

You do not have to provide any personal details to use the app. To make a purchase you need a Google account.

The purpose of all processing in this section is to provide the app's functions; the legal basis is Art. 6(1)(b) GDPR. Storing and reading on your device, including access to the camera and gallery, is strictly necessary for the functions you request (Section 25(2) no. 2 TDDDG).

3.1 Your entries and settings

In a database on your device the app stores your accounts and balances, transactions (name, amount, date, category, account, note and, where applicable, the time a receipt photo was taken), categories with budget limits, recurring payments, standing orders, reminders and savings goals. In the app's settings it stores language, currency, display mode and your selection in the forecast and the reserve calculator, plus technical markers: whether you completed the introduction, whether Premium is active, the result of the last purchase checks, whether and when you confirmed the "Purchases via Google Play" notice and when you last started a purchase.

The comparison figures from the Federal Statistical Office (Destatis) are included in the app; the app does not download them from the internet.

"Delete All Data" in the settings deletes all entries in the database and the scheduled notifications; the app then recreates the default categories. Settings and markers are kept. They are removed when you uninstall the app or clear the app's data in the Android settings.

3.2 Notifications

The app schedules notifications on your device for reminders and due payments; it does not use a push service. To do so, it stores the scheduled notifications with their content on your device: name and amount of a recurring payment or standing order, name and note of a reminder. Depending on your Android settings, notifications can also be seen on the lock screen. The app asks for the permission at start-up; you can revoke it at any time in the Android settings.

3.3 Receipt photos (Premium)

For a transaction you can take a receipt photo with the camera or choose one from the gallery; Android asks for the necessary permissions the first time. The app saves the photo in your device's gallery, not in its database; there it only remembers the time. In the gallery the photo is visible, like your other photos, to apps that have access to your photos, and it is included if you use a photo backup (for example Google Photos). The app deletes the copy created in its cache while taking or choosing the photo once it has been saved. "Delete All Data" does not remove receipt photos; you can do that in your gallery app.

3.4 Export, backup file and sharing

You create JSON backups, CSV exports and PDF reports yourself and save them wherever you like via the Android save dialog. The files are not encrypted; you decide who you give them to. You restore a backup via the Android file picker; the app deletes the copy created in its cache once it has read the file. "Share with Friends" opens the Android share menu with a short text about the app; the app itself sends nothing.

3.5 Permissions

The app uses these Android permissions: notifications and vibration for reminders, starting after the device restarts (to reschedule reminders), the camera for receipt photos, storage access (only on older Android versions, to save photos), billing via Google Play, and internet access and network state. The internet access is needed by the included Google libraries for Google Play (section 4); the app itself downloads nothing from the internet and sends nothing to me. The app does not use location, contacts or the microphone.

4.1 When the app connects to Google Play

Premium is a one-time purchase via Google Play. The app does not connect to Google Play's billing system until you tap "Continue to purchase" or "Restore purchases" on the Premium screen. The first time, it shows the "Purchases via Google Play" notice beforehand; if you tap "Cancel", it does not connect. As long as you neither want to buy nor restore purchases, the app does not connect to Google Play's billing system, and all free features remain available.

The app connects to Google Play on its own at start-up in only two cases: while Premium is active, to check that your purchase is still valid (for example after a refund), and in the 4 days after you started a purchase, so that a purchase that has not yet completed reaches the app and is acknowledged; if you cancel the purchase in Google's purchase dialog, this no longer applies. Google automatically refunds a purchase if the app does not acknowledge it within 3 days.

4.2 What data is involved

Google handles the purchase and payment. In doing so, Google processes your Google account, your payment details and the purchase data under its own terms. For your purchase, the app receives from Google Play the product ID and a purchase receipt (including the order number and time of purchase). It only evaluates whether Premium has been bought and stores only the marker from section 3.1.

In the Google Play Console, Google provides me with order data for each purchase, including order number, time, product, price, country and device model, and in some cases state or region and postal code. I can find an order by its order number or by your full email address, for example to refund it at your request. I do not receive payment details such as card numbers.

Log data from the billing library: to connect to Google Play, the app includes Google's Google Play Billing Library. As soon as the app connects to Google Play, this library writes technical log data to a cache on your device and sends it to Google in the background on its own, for example whether calls succeeded, error messages, the library version, the app's package name and version, device manufacturer and model, Android version and build, country, language, mobile network (country and operator code), network type, time zone, timestamps and a random number that is generated anew for each connection and ties together the log data of that connection. When sending, Google also receives your IP address for technical reasons. The library offers no way to switch this off.

4.3 Who is responsible

Google Play is provided by Google Ireland Limited, Gordon House, Barrow Street, Dublin 4, Ireland. You conclude the purchase contract with Google Commerce Limited, 70 Sir John Rogerson's Quay, Dublin 2, Ireland; payment is made via your Google Payments account. Google itself is responsible for the purchase and payment and is not my processor.

I am responsible for collecting the log data in the app and transmitting it to Google: I decide whether and when the app uses the library (section 4.1), and I inform you about it. Google Ireland Limited alone is responsible for the processing after receipt by Google; Google determines which data the library collects and what Google uses it for. For Google Play, the Google Controller-Controller Data Protection Terms apply, under which each party is responsible for its own processing. You can also exercise your rights regarding the data held by Google directly with Google. Google describes its processing here: https://policies.google.com/privacy

Google may transfer data to Google LLC in the USA. Google LLC is certified under the EU-US Data Privacy Framework (checked on 2 October 2026).

4.4 Legal bases

• → Storing and reading information on your device by the billing library, including its cache for log data, from the moment you want to buy or restore purchases: Section 25(2) no. 2 TDDDG.
• → Purchase, restoring and checking your purchase at start-up: Art. 6(1)(b) GDPR; where no purchase exists yet or refunds are to be detected, Art. 6(1)(f) GDPR (legitimate interest in completing purchases that have been started and in unlocking Premium only for a valid purchase).
• → Order data in the Play Console: Art. 6(1)(c) GDPR for my accounting and Art. 6(1)(f) GDPR for handling refunds and enquiries.
• → Log data from the billing library: Art. 6(1)(f) GDPR. My legitimate interest is offering Premium via Google Play's billing system, which only works with this library. I do not ask for consent for this, because you could not refuse it without giving up the purchase. You can object (section 11).

4.5 Older app versions

Older versions of the app that have not yet been updated connect to Google Play at every start, even without any intention to buy, to check the Premium status. In doing so, the billing library may send the log data listed in section 4.2 to Google. Please update the app.

If you tap "Rate App" under "More", the app asks Google Play to show the rating dialog; Google decides whether it appears. The rating is handled entirely by Google Play, and Google alone is responsible for it. The app does not learn whether or how you rate it. I see public reviews in the Play Console with the displayed name, stars, text and date as well as technical details supplied by Google (for example device model, Android version, app version and language), and I can reply to them publicly there. The legal basis for this is Art. 6(1)(f) GDPR (legitimate interest in feedback on the app and in replying to it).

If Android backup is switched on on your device, Android backs up the data of apps to your Google account. For Budget Book this includes the database with your entries, the scheduled notifications and the settings including markers (sections 3.1 and 3.2), but not receipt photos in the gallery. This lets you transfer your data to a new device. From Android 9, Android encrypts the backup end-to-end with your device's PIN, pattern or password, provided you have set a screen lock. You choose in the Android settings whether backups are made; I have no access to the backup. Google is responsible for the backup (https://policies.google.com/privacy). The app's participation in the backup is based on Art. 6(1)(b) GDPR: it lets you take your data with you when you change devices.

If you have agreed on your device to share usage and diagnostics data with Google automatically, Android also sends information about crashes and the performance of this app to Google. This is an Android setting, not an app setting; Google is responsible. From this, Google provides me with reports in the Play Console (Android Vitals), for example crash causes with device model and Android version, without names or contact details. I use them to fix bugs. The legal basis for this is Art. 6(1)(f) GDPR (legitimate interest in a bug-free app).

When you visit pages on signalbytestudio.de, including this policy, the website's privacy policy applies (in German): https://signalbytestudio.de/datenschutz

If you write to me, I process your email address and the content of your message to answer your enquiry. The legal basis is Art. 6(1)(b) GDPR where it concerns a purchase or the use of the app, otherwise Art. 6(1)(f) GDPR (legitimate interest in answering enquiries). My mailbox is provided by GMX (1&1 Mail & Media GmbH, registered office Montabaur, Local Court of Montabaur, HRB 7666); your emails are stored there.

You have the right of access (Art. 15 GDPR), rectification (Art. 16 GDPR), erasure (Art. 17 GDPR), restriction of processing (Art. 18 GDPR), data portability (Art. 20 GDPR) and to object (Art. 21 GDPR, see section 11). An email to signalbytestudio@gmx.de is sufficient.

Your entries are stored on your device. There you can view, change, delete and export them as a file at any time; I can neither see them nor delete them for you. I can only match data held by me (emails, order data) to you if you give me a reference, for example your email address or an order number. For matters concerning the data held by Google, you can contact me or Google directly; only Google can provide information about this data.

You also have the right to lodge a complaint with a data protection supervisory authority (Art. 77 GDPR), for example with the State Commissioner for Data Protection and Freedom of Information Baden-Württemberg, which is responsible for me, Heilbronner Straße 35, 70191 Stuttgart, Germany.

Where I process data on the basis of legitimate interests (Art. 6(1)(f) GDPR, sections 4, 5, 7 and 9), you can object at any time on grounds relating to your particular situation. An email to signalbytestudio@gmx.de is sufficient.

• → Entries, settings, markers and scheduled notifications on your device: until you delete them, uninstall the app or clear the app's data in the Android settings. "Delete All Data" removes the entries and the scheduled notifications, but not settings and markers (section 3.1).
• → Receipt photos: in your gallery until you delete them there.
• → Android backup: according to the rules of your Google account.
• → Log data from the billing library: on your device until uploaded; the library deletes entries older than 7 days unsent at its next upload attempt. Google decides how long it keeps the uploaded data.
• → Purchase and payment data at Google: according to Google's periods. Order data in the Play Console: for as long as Google provides it there; I cannot delete it there. Reports I store for my accounting are kept for the statutory retention periods.
• → Reviews: for as long as they are published on Google Play; you can delete them there.
• → Crash and performance reports (Android Vitals): available for 90 days in the Play Console and for 3 years via Google's programming interface (Play Developer Reporting API).
• → Emails: until your enquiry has been dealt with; longer only if a statutory retention obligation applies (Art. 6(1)(c) GDPR), and then until it expires.
• → Website logs: see the website's privacy policy (section 8).

I make no automated decisions within the meaning of Art. 22 GDPR. The app calculates forecasts, suggestions and analyses on your device only for you.

I update this policy when the app or the legal situation changes. The version on the website is authoritative (https://signalbytestudio.de/budget-book/privacy); the version shown in an older app version may be out of date.

Last updated: 2 October 2026