Privacy Policy

Your Data Stays on Your Device

All your personal data stays on your device. Your Premium Bonds holdings, financial calculations, word lists, and learning progress are stored only on your device. We never see, store, or transmit this information. Your device is your vault.

We collect only anonymous analytics (device type, app usage patterns, crash reports) to improve the apps. This data cannot identify you personally.

Introduction

Stack Studio ("we," "our," or "us") operates mobile applications and the website https://stackstudio.uk. This Privacy Policy explains how we collect, use, disclose, and protect your information when you use our apps (NUMO, WORDSTASH) and website.

By using our services, you agree to the collection and use of information in accordance with this policy.

How Our Apps Work

Your Data Stays on Your Device

NUMO App:

  • Premium Bonds holdings and tracking data
  • Financial calculation inputs (savings amounts, interest rates, mortgage details)
  • User preferences and settings

WORDSTASH App:

  • Custom word lists and vocabulary entries
  • Learning progress and statistics
  • User preferences and notification settings

This data is stored locally on your device only. We never collect, see, access, or transmit this information. It never leaves your device.

Information We Collect

We use PostHog, a privacy-focused analytics platform, to understand how our apps are used and to improve them. PostHog collects anonymous analytics data only:

  • Device information: Device type, operating system version
  • App usage statistics: Which features you use, how often, and basic interaction patterns (not what you enter in them)
  • Crash reports and diagnostic data: Technical information to help us fix bugs
  • Anonymous identifiers: A randomly generated ID that doesn't identify you personally


We do not collect:

  • Your name, email address, or contact information
  • IP addresses (these are anonymized by PostHog)
  • Your personal app data (Premium Bonds amounts, word lists, calculation inputs, etc.)
  • Any information that can personally identify you


How We Use Your Information

We use analytics data collected through PostHog for:

  • App Improvement: Understanding which features are used most and identifying areas for improvement
  • Bug Fixes: Detecting crashes and technical issues to improve app stability
  • Performance Optimization: Analyzing app performance to make our apps faster and more reliable
  • Feature Development: Understanding user behavior to build features that matter most

We do not use your data for:

  • Advertising or marketing
  • Selling to third parties
  • Tracking you across other apps or websites
  • Creating user profiles for commercial purposes

Data Storage and Security

Analytics Data Security

Anonymous analytics data collected by PostHog is:

  • Transmitted using encrypted HTTPS connections
  • Stored securely on PostHog's servers (see PostHog's security practices)
  • Automatically anonymized (IP addresses are not stored)
  • Never sold or shared with advertisers

Your Control

  • You can delete all your personal data at any time by deleting the app
  • Analytics data cannot be linked back to you personally
  • No account creation or login is required


Data Sharing and Disclosure

We do not sell your data. Period.

  • PostHog Analytics: We use PostHog, a privacy-focused analytics service, to collect anonymous usage statistics. PostHog processes this data on our behalf and does not use it for any other purpose. You can learn more about PostHog's privacy practices at posthog.com/privacy.
  • Legal Requirements: We may disclose information if required by law, regulation, legal process, or governmental request.
  • No Other Sharing: We do not share, sell, or rent your information to any other third parties for marketing or advertising purposes.

Your Rights and Choices

Your Personal Data

Since your personal app data (Premium Bonds, word lists, etc.) is stored only on your device:

  • Complete Control: You have full control over this data
  • Delete Anytime: Simply delete the app to remove all your personal data
  • No Account Required: No registration means no data to request or delete from our servers


Analytics Data

The anonymous analytics data we collect through PostHog:

  • Cannot identify you personally: It's anonymized and not linked to you
  • Opt-out available: You can contact us to opt out of analytics (though this limits our ability to improve the apps)


Notifications (WORDSTASH)

  • Your Choice: Enable or disable daily word notifications in the app settings
  • Local Only: Notification preferences are stored on your device


Children's Privacy

Our apps are not intended for children under 13 years of age. We do not knowingly collect personal information from children under 13. If you are a parent or guardian and believe your child has provided us with personal information, please contact us.

International Users

If you are accessing our services from outside the United Kingdom, please note that your information may be transferred to, stored, and processed in the UK or other countries where our service providers operate.

Changes to This Privacy Policy

We may update this Privacy Policy from time to time. We will notify you of any changes by:

  • Updating the "Last Updated" date at the top of this policy
  • Posting the new Privacy Policy on our website
  • Providing an in-app notification for significant changes


Contact Us

If you have questions, concerns, or requests regarding this Privacy Policy or our data practices, please contact us:

Stack Studio


Email: [Your Email Address]


Website: https://stackstudio.uk

App-Specific Information

NUMO Privacy Details

  • No Account Connection: NUMO does not connect to your actual Premium Bonds account, NS&I, or any financial institutions
  • Local Storage Only: All financial data you enter is stored only on your device
  • No Sharing: Your Premium Bonds holdings and financial calculations never leave your device
  • No Credentials: We never collect or store banking credentials, account numbers, or passwords


WORDSTASH Privacy Details

  • Your Vocabulary: Your custom word lists and learning progress are stored only on your device
  • No Sharing: Your word lists are private and never shared with other users or stored on our servers
  • No Advertising: We don't use your vocabulary data for advertising or any commercial purposes


Legal Basis for Processing (GDPR)

For users in the European Economic Area (EEA) and UK: Since your personal app data is stored only on your device and never transmitted to us, GDPR applies only to the anonymous analytics data we collect through PostHog.

We process anonymous analytics data based on:

  • Legitimate Interests: To improve our apps, fix bugs, and understand how features are used while protecting your privacy through anonymization


Cookies and Tracking Technologies

Website: Our website may use cookies for basic functionality. You can control cookies through your browser settings.

Mobile Apps: Our apps use PostHog's analytics SDK, which may use local device storage to track anonymous usage statistics. This is not the same as web cookies and does not track you across apps or websites.

Your privacy matters to us. We are committed to protecting your information and being transparent about our practices.