LangsiPrivacy Policy
Last updated: October 2026
1. Data Controller
Data Informed Decisions LLC
Represented by: Axel Köcher
Fort Lauderdale, FL 33309, USA
Email: info@data-informed-decisions.com
Phone: +1 302 520 5834
2. International availability and analytics
Langsi is an internationally available language-learning service operated by Data Informed Decisions LLC, Florida, USA. Availability of particular interface or learning languages does not indicate geographic targeting; languages are offered to users worldwide regardless of their location. Subscription prices are stated in US dollars.
Langsi uses analytics technologies to understand the use and performance of the service and to improve its functionality. Analytics tracking can be disabled by users through the available privacy settings.
Core account functionality is limited to the information necessary to provide the service, including account identification such as an email address and the storage of individual learning progress. Langsi does not require users to provide special-category personal data for ordinary use of the service.
Users remain free to use the service without optional analytics tracking where technically available. Further information about data processing, analytics providers, retention and available privacy controls is provided in the Privacy Policy.
3. Data Protection Contact
For all privacy inquiries, please contact: info@data-informed-decisions.com
4. Purposes of processing
We process personal data only where needed: to provide the service you requested (account, learning progress, subscription management); with your consent (optional analytics and advertising measurement, optional email summaries); to meet legal obligations (for example tax and accounting records); and for legitimate operational purposes such as security, abuse prevention and service stability.
5. Hosting (Base44)
The Langsi platform is hosted via Base44. Server infrastructure, authentication services and database services are provided by Base44 Inc. Basis: providing the service; legitimate operational interests.
6. Server Log Files
When accessing our platform, the following data is automatically stored in server log files:
- IP address of the requesting device
- Date and time of the request
- Requested URL
- Browser type and version
- Operating system
- HTTP status code
Retention period: 30 days, then automatic deletion. Basis: legitimate operational interests (security, stability).
7. User Accounts and Registration
Registration is required to use Langsi. We process:
- Email address
- Password (stored encrypted, no plaintext)
- Full name (optional, transmitted via Google login)
- Login timestamp and method (email/Google)
- User role (standard user or administrator)
Basis: providing the service you requested. For Google login: Google LLC, Mountain View, California, USA (privacy policy: policies.google.com/privacy).
8. Learning Progress Data
To provide the core service, we store learning progress data, in particular:
- Learned and reviewed vocabulary (Leitner box system)
- Day-based learning sessions (date, goals, progress)
- Response times and error rates per vocabulary item
- Learning streak and overall statistics
- Preferred learning modes and settings
- Selected learning languages and daily learning goals
Basis: providing the service you requested. Retention: until account deletion.
9. Teacher Accounts and Classes
Teachers can create a teacher profile. The public details (display name, institution, city, country, website and short description) are visible to students they invite and to connected students. Postal address and phone number are private and are not shown to students.
Teachers can invite students by email address. We store this address to match the invitation to the right account and send an invitation email. If the invited person declines the invitation or disconnects, they will not be contacted again on that teacher's behalf.
Only after the student has accepted the invitation (consent) can the teacher see the student's learning progress, and only on that teacher's own lists (words seen and learned, correct and incorrect answers, last activity). Teachers do not see any other learning data.
Students can withdraw their consent at any time by disconnecting from the teacher in their profile. The teacher then no longer has access; the student's own learning progress remains in the student's account.
Teachers are responsible for the content of their lists. Classes are used only to assign lists to students.
The minimum age requirements in our Terms of Service remain unchanged.
10. Cookies and Local Storage
Necessary Cookies / Session Token
Authentication tokens for logged-in users. Without these cookies the platform cannot be used. Basis: providing the service you requested.
Local Storage (Learning Settings)
Storage of user preferences such as font size, preferred learning mode and UI settings in the browser. Basis: providing the service; legitimate operational interests.
Analytics Cookies (Google Analytics) – only after consent
Google Analytics 4 is loaded only after your explicit consent via the cookie banner. Without consent, no analytics cookies are set. Basis: your consent.
Revoke consent: Privacy Settings
Marketing Cookies (Meta/Facebook Pixel) – only after consent
We use the Meta (Facebook) Pixel to measure and optimize our advertising campaigns and to build custom/lookalike audiences for future campaigns. It is loaded only after your explicit consent via the cookie banner and records page views and conversion events (e.g. account registration). Provider: Meta Platforms, Inc., Menlo Park, California, USA. Without consent, no Meta Pixel cookies are set and no data is shared with Meta. You can object to this processing (and to being included in Meta's Custom/Lookalike Audiences) via your Facebook ad settings (Off-Facebook Activity) in addition to revoking consent here. Meta's privacy policy: facebook.com/privacy/policy. Basis: your consent.
Revoke consent: Privacy Settings
Marketing Cookies (Google Ads Conversion Tracking) – only after consent
We use Google Ads conversion tracking to measure which of our ad campaigns lead to a lead or a completed registration, and to optimize future campaigns accordingly. It is loaded only after your explicit consent via the cookie banner and records specific conversion events (e.g. account registration) — no general page-view tracking beyond what Google Analytics 4 already covers. Provider: Google LLC, Mountain View, California, USA. Without consent, no Google Ads conversion cookies are set and no conversion data is shared with Google. You can object to this processing via Google's ad settings (adssettings.google.com) in addition to revoking consent here. Google's privacy policy: policies.google.com/privacy. Basis: your consent.
Revoke consent: Privacy Settings
11. Payment Processing (Stripe)
Paid services are processed via Stripe, Inc., USA. Payment data (credit card details, billing address etc.) is transmitted directly to Stripe. Langsi does not receive or store complete payment instrument information. We store internally: Stripe customer ID, subscription ID, plan, status and term data – solely for subscription management. Stripe privacy policy: stripe.com/privacy. Basis: providing the service you requested.
12. Analytics (Google Analytics 4)
We use Google Analytics 4 to analyze platform usage, provided you have consented. Provider: Google LLC, Mountain View, California, USA. Google Analytics is only loaded after your consent via the cookie banner. Google Analytics 4 does not log or store IP addresses. Google privacy policy: policies.google.com/privacy. Basis: your consent.
Revoke consent: Privacy Settings
13. Email Dispatch (Resend)
For sending emails (welcome emails, daily learning summaries, OTP verification codes) we use Resend Inc., San Francisco, California, USA. Email address and message content are transmitted to Resend. Basis: providing the service you requested (transactional emails); your consent (optional summaries after consent in profile settings).
14. AI Services (Language Models)
To generate vocabulary, example sentences, personalized learning content and AI coaching messages, we use AI language models. Requests contain exclusively language-related content (words, learning context) and no directly personal user data. Services used via the Base44 platform include Google Gemini (Google LLC). Basis: providing the service; legitimate operational interests.
15. Text-to-Speech Services (TTS)
For vocabulary pronunciation, we use text-to-speech services. Vocabulary and example sentences (no personal data) are transmitted to external TTS providers. Primary service: Web Speech API (browser-native, Google Chrome TTS) – data processing in the user's browser; for cloud services: Google LLC. Basis: providing the service you requested.
16. Data storage and transfers
Langsi and its service providers process data on servers in the United States and other countries. We work with service providers that contractually commit to appropriate data protection safeguards.
17. Retention Periods
18. Your privacy rights
Regardless of where you live, you can request access to the personal data we store about you, its correction or deletion, restriction of processing, and a copy of your data in a portable format. You can object to processing and withdraw any consent at any time with effect for the future. To exercise your rights, contact: info@data-informed-decisions.com
19. Right to Withdraw Consent
Where processing of your data is based on consent, you have the right to withdraw it at any time with effect for the future. Withdrawal possible via:
- Privacy Settings in the App
- Profile page > Notification settings (for email summaries)
- By email: info@data-informed-decisions.com
- Request Account Deletion
20. Questions and concerns
If you have a concern about how we handle your data, please contact us first at info@data-informed-decisions.com. You may also contact the data protection authority in your country.
21. Account Deletion and Data Erasure
You can delete your account and all associated data at any time via: Profile > Account Information > Delete Account. Deletion covers: learning progress data, daily sessions, UserSettings and all personal configurations. Billing data is retained as required by law. Alternatively by email: info@data-informed-decisions.com – processed within 30 days.