Youyin

Privacy & Data Protection

Privacy Policy

Last updated: 5 October 2026

Youyin is built with a local-first, privacy-by-design architecture. Your learning progress, custom flashcards, and preferences are stored exclusively on your own device and are never transmitted to a remote server.

100% Local Storage

All cards, phrases, stats, and streak history live in your browser's IndexedDB.

No Accounts or Sign-up

Use Youyin freely without creating an account, providing an email, or setting a password.

No Tracking or Ads

Zero analytics trackers, zero profiling scripts, and zero advertising cookies.

Full Data Control

Export your decks to JSON or erase all local data in one click at any time.

This Privacy Policy explains how Heapforge Ltd. (“Heapforge”, “we”, “us” or “our”) collects, uses, shares and protects personal data when you visit https://youyin.madladsquad.com, use Youyin, or otherwise contact us. It also explains the rights you have and how to exercise them.

1. Who we are


The data controller responsible for your personal data is Heapforge Ltd., registered in England and Wales:

Company
Heapforge Ltd.
Company number
17418393
Registered office
82A James Carter Road, Mildenhall, Bury St. Edmunds, Suffolk, England, IP28 7DE, United Kingdom
Privacy contact
privacy@heapforge.com

2. Scope


This policy applies to personal data we process through this service, as well as when you communicate with us. It does not apply to third-party websites or services that we link to, which have their own privacy policies.

3. Personal data we collect


We try to collect only what we need. Depending on how you interact with us, this may include:

We do not intentionally collect special category data (such as health, religious or biometric data). Please do not send us such information unless we have specifically asked for it.

4. How we use personal data and our lawful bases


Under the UK and EU GDPR, we must have a lawful basis for each use of your personal data.

PurposeLawful basis
Delivering our website and services to youLegitimate interests (operating our website and business); contract, where you use our services
Protecting our website and services from abuse, fraud, bots and attacksLegitimate interests (keeping our services and users secure)
Responding to your emails and enquiriesLegitimate interests (communicating with people who contact us); contract, where the enquiry relates to a service you use or are about to use
Providing, managing and supporting services you have purchasedContract
Keeping business records and meeting legal, tax and regulatory obligationsLegal obligation
Establishing, exercising or defending legal claimsLegitimate interests
Any purpose for which we ask for your consentConsent (which you can withdraw at any time)

Where we rely on legitimate interests, we have considered whether those interests are outweighed by your rights and freedoms. You can contact us for more information about this balancing.

We do not sell your personal data.

5. Third-party service providers


We use a number of trusted service providers to run our business. They process personal data on our behalf and under our instructions, and are bound by contractual obligations to protect it. Our main providers are listed below.

5.1 Cloudflare

We use services provided by Cloudflare, Inc. to host, deliver and protect our website:

Cloudflare operates a global network, so your data may be processed in data centres close to your location, including outside the UK and EU. For more information, see Cloudflare's Privacy Policy: https://www.cloudflare.com/privacypolicy/

5.2 Google Workspace

We use Google Workspace, provided by Google, as our email provider. When you email us, your message – including your name, email address, message content, attachments and related metadata – is received, stored and processed on Google's systems. Google processes this data on our behalf under its business data processing terms and does not use Workspace customer data for advertising.

For more information, see Google's Privacy Policy (https://policies.google.com/privacy) and Google Cloud Privacy Notice (https://cloud.google.com/terms/cloud-privacy-notice).

5.3 Other recipients

We may also share some personal data with:

6. Cookies and similar technologies


We only use cookies and similar technologies that are strictly necessary for our website to function securely, such as security cookies to distinguish genuine visitors from automated bots. These do not require your consent under UK and EU law, and we do not use them to track you across other websites.

If we introduce non-essential cookies (for example, for analytics or advertising), we will update this policy and, where required by law, ask for your consent before setting them.

7. International data transfers


We are based in the United Kingdom, and some of our service providers process data in other countries, including the United States.

Where personal data is transferred outside the UK or the European Economic Area (EEA), we ensure appropriate safeguards are in place, such as:

You can contact us for more information about the safeguards we use.

8. How long we keep personal data


We keep personal data only for as long as necessary for the purposes described in this policy, including to meet legal, accounting or reporting requirements. As a general guide:

When data is no longer needed, we delete or anonymise it securely.

9. How we protect personal data


We use appropriate technical and organisational measures to protect personal data against unauthorised access, loss, misuse or alteration. These include encryption in transit, access controls and choosing reputable providers with strong security practices. No method of transmission or storage is completely secure, however, and we cannot guarantee absolute security.

If a personal data breach occurs that is likely to put your rights at risk, we will notify you and the relevant authorities as required by law.

10. Your rights (UK, EU, EEA and Switzerland)


If you are in the UK, EU, EEA or Switzerland, you have the following rights, subject to certain conditions and exceptions:

To exercise any of these rights, email us at privacy@heapforge.com. We will respond within one month, which may be extended by up to two further months for complex requests. We may need to verify your identity before responding. Exercising your rights is usually free of charge.

11. Other countries


If you live in another country with privacy laws that give you rights over your personal data, please contact us and we will respond in accordance with the law that applies to you.

12. Children's privacy


Our website and services are not directed at children under the minimal age for data processing consent, and we do not knowingly collect personal data from them. If you believe a child has provided us with personal data, please contact us and we will delete it.

13. Automated decision-making


We do not make decisions about you based solely on automated processing that produce legal or similarly significant effects. Automated security tools (such as bot protection) may block or challenge suspicious traffic; if you believe you have been blocked in error, please contact us.

14. Links to other websites


Our website may contain links to third-party websites or services. We are not responsible for their privacy practices, and we encourage you to read their privacy policies.

15. Changes to this policy


We may update this policy from time to time. The “Last updated” date at the top shows when it was last revised. If we make significant changes, we will take reasonable steps to let you know, for example by a notice on our website.

16. Contact us and complaints


If you have any questions about this policy or how we handle your personal data, please contact us:

  1. E-mail: privacy@heapforge.com
  2. Post: Heapforge Ltd., 82A James Carter Road, Mildenhall, Bury St. Edmunds, Suffolk, England, IP28 7DE, United Kingdom

We would appreciate the chance to address your concerns first, but you have the right to complain to a data protection authority: