Last updated: 13.02.2026
We value your privacy and are committed to protecting your personal data.
This Privacy Policy explains how zerozerofournine.com and the mobile application “Deutsch Deck” (iOS & Android) collect, process, and safeguard your information in accordance with the EU General Data Protection Regulation (GDPR) and other applicable privacy laws.
This policy applies to:
Our website: zerozerofournine.com
The mobile app: Deutsch Deck
Related digital services, purchases, subscriptions, newsletters, and communications
Srijith Kariyattil (Einzelunternehmen)
trading as Zero Zero Four Nine
c/o Postflex #9448
Emsdettener Str. 10
48268 Greven
Germany
Email: srijith@zerozerofournine.com
When you visit our website, contact us, or purchase our products, we may collect:
Personal Information
Your name
Email address
Contact details
Information submitted via contact forms
Newsletter subscription information
Transaction Data
Billing information
Order details
Payment confirmation
Payment information is processed securely by third-party providers. We do not store full payment card details.
Technical Data
IP address
Browser type
Operating system
Referrer URL
Device information
Cookies and analytics data
When using the Deutsch Deck app, we may collect:
Account Data
Name
Email address
Country (optional)
Profile photo (optional)
Encrypted login credentials
Authentication is handled securely via Firebase Authentication.
Study & Learning Data
To provide flashcard functionality, we process:
Selected CEFR level (A1–C2)
Selected card type (Basic, Full, Nouns, Verbs, Adjectives, Phrases, Grammar)
Flashcard ratings (Again, Good, Easy)
Spaced repetition intervals
Deck mastery percentage
Study progress per level/type combination
Streak count
Daily goal settings
Session duration
Weekly statistics
Success rate calculations
Leaderboard ranking
Technical & Usage Data (App)
Collected automatically to maintain performance and security:
Device model
Operating system version
App version
Crash logs
Diagnostic data
Anonymous analytics data
Push Notifications
If enabled, we may process:
Reminder times
Notification tokens
Study reminders
Streak reminders
Push notifications can be disabled at any time via device settings.
We process personal data under the following legal bases:
For:
Providing website purchases
Providing app functionality
Managing user accounts
Delivering flashcard learning features
Maintaining streaks and progress
Enabling leaderboard functionality
Managing subscriptions
For:
Newsletter subscription
Marketing emails
Non-essential cookies
Push notifications (where required)
You may withdraw consent at any time.
For:
Improving app stability
Preventing abuse or fraud
Ensuring system security
Analyzing performance
Maintaining operational integrity
Our website uses cookies to improve your experience, measure website performance, and tailor content. Essential cookies necessary for operation are always active.
Non-essential cookies (analytics/marketing) require your consent and can be managed via:
Cookie banner
Browser settings
We share your personal data only with service providers essential for our operations under Data Processing Agreements (Art. 28 GDPR).
Squarespace (Hosting)
Stripe (Payment processing)
PayPal (Payment processing)
ConvertKit (Email marketing)
Google Firebase (Google Ireland Ltd.)
Authentication
Firestore Database
Cloud Functions
Storage
Analytics
Crashlytics
Apple App Store
Google Play Store
We do not sell personal data.
We use ConvertKit to manage subscriber lists and send emails.
If you subscribe:
Your name and email are transferred to ConvertKit servers (USA).
Transfers are protected via Standard Contractual Clauses (SCCs).
You may unsubscribe anytime via the email link.
ConvertKit Privacy Policy:
https://convertkit.com/privacy
Some providers may process data outside the EU/EEA. Where this occurs, we ensure safeguards under:
Art. 44–49 GDPR
Standard Contractual Clauses (SCCs)
For as long as your account remains active
As necessary to fulfill contractual obligations
In accordance with German tax and commercial retention obligations (typically 6–10 years for invoices and accounting records)
Until consent is withdrawn (marketing communications)
Upon account deletion:
Personal data is erased
Study data is permanently removed
Leaderboard entries are deleted
If you participate in the app leaderboard:
Your chosen display name
Profile photo (if uploaded)
Country (if provided)
Streak data
may be visible to other users within the app. You may modify your display name at any time.
We implement appropriate technical and organizational measures including:
SSL/TLS encryption
Encrypted cloud infrastructure
Access controls
Secure authentication mechanisms
Regular system updates
Restricted internal access
While we take reasonable measures, no online transmission is 100% secure.
If you are in the EU or EEA, you have the right to:
Access your data (Art. 15)
Rectify inaccurate data (Art. 16)
Erase your data (Art. 17)
Restrict processing (Art. 18)
Data portability (Art. 20)
Object to processing (Art. 21)
Withdraw consent at any time
To exercise your rights, contact: srijith@zerozerofournine.com
You have the right to lodge a complaint with a supervisory authority in Germany. The competent authority depends on your federal state.
The app uses algorithm-based spaced repetition scheduling to optimize learning. This does not constitute automated decision-making within the meaning of Art. 22 GDPR and does not produce legal or similarly significant effects.
While we use SSL encryption, secure storage systems, and access restrictions, we cannot guarantee absolute security of information transmitted online.
We may update this Privacy Policy to reflect legal, technical, or operational changes.
The latest version will always be available:
On our website
Inside the app
© Copyright 0049 Zerozerofournine