Last updated: September 14, 2026

Terms and Conditions

The Short Version

These are the rules for using SifuLingo. The main points: be respectful, don't abuse the service, subscriptions are handled by Paddle, and you can cancel anytime with a 30-day money-back guarantee. If something goes wrong or you have questions, reach out - I'm happy to help work things out.

I wrote these terms to be clear and fair, not to hide behind legal jargon. If something's unclear, let me know.

1. Agreement to Terms

By using SifuLingo (the website, web app, and all related services at sifulingo.de), you agree to these terms. If you don't agree, please don't use the service.

SifuLingo is operated as a solo project. I'm currently running it as a freelancer/solopreneur, with plans to formally register as a business. For any questions or concerns, you can reach me at [email protected].

2. What SifuLingo Is

SifuLingo is a language learning app that helps you build and retain vocabulary using:

  • Spaced repetition flashcards for effective memorization
  • OCR scanning to extract words from images
  • AI-powered vocabulary suggestions tailored to your level
  • AI-generated practice stories
  • Audio pronunciation for words
  • Progress tracking and learning analytics

What it's not: SifuLingo is a vocabulary-focused tool, not a complete language learning course. It won't teach you grammar, conversation skills, or cultural context on its own. Think of it as a powerful vocabulary trainer that works alongside your other learning methods.

3. Account Requirements

To use SifuLingo, you need to:

  • Be at least 16 years old (GDPR requirement)
  • Provide accurate information when signing up (name and email)
  • Keep your password secure - you're responsible for activity on your account
  • Use the service personally - don't share your account with others

If you notice unauthorized access to your account, let me know immediately at [email protected].

4. Subscription Plans & Pricing

SifuLingo offers subscription-based access with different tiers. Current pricing and plan details are available on the pricing page.

Why Subscription?

Running SifuLingo isn't free - there are ongoing costs for AI processing (OpenAI, Google Gemini), hosting, storage, and email delivery. A subscription model lets me cover these costs while keeping the service running and improving it over time. I've kept pricing as reasonable as possible for a solo operation.

Payment Processing

All payments are processed by Paddle, the merchant of record. This means:

  • Paddle handles all payment information - I never see your credit card details
  • Paddle manages VAT/tax compliance automatically based on your location
  • Your payment receipts and invoices come from Paddle
  • Paddle's terms and policies also apply to payment transactions

Billing Cycle

  • Monthly subscriptions: Billed every month on the date you subscribed
  • Yearly subscriptions: Billed annually on the date you subscribed
  • Subscriptions automatically renew unless you cancel
  • Price changes will be communicated 30 days in advance and apply at your next renewal

5. Refund Policy

I want you to be happy with SifuLingo. If it's not working for you, here's how refunds work:

30-Day Money-Back Guarantee

Both monthly and yearly subscriptions come with a 30-day money-back guarantee from the date of purchase. If you're not satisfied within the first 30 days, email me at [email protected] and I'll process a full refund through Paddle.

After 30 Days

  • Monthly subscriptions: You can cancel anytime, and you won't be charged for the next month. However, the current month's payment is not refundable after 30 days.
  • Yearly subscriptions: You can cancel the auto-renewal anytime to prevent the next year's charge, but the current year's payment is not refundable after 30 days.

Fair Use

The refund policy is meant for genuine cases where the service doesn't meet your needs. If there's a pattern of abuse (repeatedly subscribing and refunding), I reserve the right to refuse future refunds or service access.

6. Cancellation

You can cancel your subscription anytime from your account settings or by contacting [email protected].

When you cancel:

  • You retain access to premium features until the end of your current billing period
  • You won't be charged again after the current period ends
  • Your account and data remain intact - you can resubscribe later if you want
  • To permanently delete your account and all data, use the account deletion option in settings

7. Acceptable Use

SifuLingo is meant for personal language learning. Here's what's not allowed:

  • No abuse or excessive use: Don't try to overwhelm the AI services with automated requests or unreasonable usage that drives up costs
  • No account sharing: Each account is for one person - don't share login credentials
  • No illegal content: Don't scan or submit content that's illegal, offensive, or violates others' rights
  • No scraping or automation: Don't use bots or scripts to extract data or automate interactions
  • No reverse engineering: Don't attempt to copy, modify, or extract the source code
  • No reselling: Don't resell access to SifuLingo or use it to provide commercial services

If you violate these terms, I may suspend or terminate your account. In extreme cases, I may do so without a refund.

8. Content & Intellectual Property

Your Content

You retain ownership of the flashcards you create and the words you add. However, by using SifuLingo, you grant me a license to process and store this content to provide the service (e.g., showing you flashcards, generating AI suggestions).

Future consideration: I may use anonymized, aggregated learning data (like common vocabulary words or topics) to improve AI recommendations. If this happens, I'll update the privacy policy and notify users. Personal information will never be used for training.

My Content

Everything else - the SifuLingo platform, code, design, AI-generated stories, audio files, branding - belongs to me. You can't copy, redistribute, or reuse it without permission.

Third-Party Content

When you scan text from books, articles, or other sources, you're responsible for ensuring you have the right to process that content. SifuLingo is a tool for personal learning - don't use it to infringe on copyrights or redistribute protected content.

9. AI-Generated Content

SifuLingo uses AI (OpenAI and Google Gemini) to generate vocabulary suggestions and practice stories. Here's what you should know:

  • Not always perfect: AI-generated content might occasionally contain errors, inaccuracies, or inappropriate suggestions. If you spot something wrong, let me know so I can improve the prompts.
  • Not a substitute for human teachers: Use AI content as a learning aid, not gospel truth. Cross-reference with other resources when learning.
  • Your data powers your experience: The AI uses your learning preferences and level to personalize content - it doesn't have access to other users' data.

10. Service Availability

I work hard to keep SifuLingo running smoothly, but as a solo operation, I can't guarantee 100% uptime. Here's the reality:

  • Maintenance: I may need to take the service down briefly for updates or fixes. I'll try to schedule these during low-traffic times.
  • Third-party dependencies: If OpenAI, Google, Paddle, or my hosting providers have issues, it affects SifuLingo too.
  • Bug fixes: I fix bugs as quickly as I can, but being a solo developer means some issues might take time.

If there's extended downtime or a major issue, I'll communicate via email and work to resolve it. If you're affected by significant downtime, reach out - I'm reasonable about adjustments or refunds for genuine service problems.

11. Disclaimers & Limitations

This is the legally required section where I have to say:

"As-Is" Service

SifuLingo is provided "as is" without warranties of any kind, express or implied. I don't guarantee that it'll meet all your needs, work perfectly all the time, or be completely error-free. I'm constantly improving it, but it's not perfect.

Not Responsible For

  • Learning outcomes - language learning depends on many factors beyond this app
  • Third-party service issues (OpenAI, Google, Paddle, hosting providers)
  • Data loss due to bugs or technical issues (though I do my best to prevent this)
  • Indirect damages or lost opportunities related to service use

Limitation of Liability

To the maximum extent permitted by law, my total liability for any claims related to SifuLingo is limited to the amount you paid for the service in the past 12 months. This doesn't affect your consumer rights under EU law where such limitations aren't allowed.

12. Termination

Either of us can end this agreement:

  • You can: Cancel your subscription or delete your account anytime
  • I can: Suspend or terminate your account if you violate these terms, abuse the service, or engage in fraudulent activity
  • Service shutdown: If I decide to shut down SifuLingo entirely (hope not!), I'll give at least 30 days' notice and provide refunds for unused subscription time

13. Changes to Terms

I may update these terms occasionally to reflect changes in the service, legal requirements, or new features. When I do:

  • The "Last updated" date at the top will change
  • For significant changes, I'll notify you by email at least 30 days in advance
  • Continued use after changes means you accept the updated terms
  • If you don't agree with changes, you can cancel and get a prorated refund for unused time

14. Governing Law & Disputes

These terms are governed by German law. Any disputes will be resolved under German jurisdiction.

But honestly: Before going to court, just email me at [email protected]. I'm a reasonable person running a small service - most issues can be worked out through conversation. Legal action should be a last resort for both of us.

EU Consumer Rights

If you're an EU consumer, you have additional rights under EU consumer protection law that cannot be limited by these terms. This includes the right to withdraw from the purchase within 14 days, though this is covered by our 30-day money-back guarantee anyway.

15. Contact & Support

For questions, support, feedback, or any concerns about these terms:

Email: [email protected]

I'm a solo developer, so you'll be communicating directly with the person who built SifuLingo. Response times are usually within 24-48 hours, though complex issues might take longer.

Final Note

I built SifuLingo to solve a real problem I had with language learning, and I hope it helps you too. These terms are meant to be fair and clear - not to create a one-sided agreement hidden behind legal complexity.

If something here seems unreasonable or unclear, let me know. I'm open to feedback and want to create a service that works for both of us.

Thanks for using SifuLingo!