Last updated: 02-09-2026
MONO ("the app") is developed and operated by Yuri van der Putten (Goudboom Enterprise), an independent developer based in the Netherlands. By downloading, installing or using the app you agree to these terms. If you do not agree, do not use the app.
MONO applies a colour filter overlay on top of your screen, optionally on a schedule. It is a comfort and preference tool. It is not a medical device, it does not diagnose, treat or prevent any condition, and no claim is made about effects on eye health, sleep or screen-time habits. If you have concerns about your eyes or sleep, consult a qualified professional.
You are granted a personal, non-exclusive, non-transferable, revocable licence to use the app on devices you own or control, for personal, non-commercial use. You may not copy, modify, reverse engineer, decompile, redistribute, resell or sublicense the app or any part of it, except where such restriction is prohibited by applicable law.
All rights in the app, its source code, design, name and branding remain with Goudboom Enterprise.
MONO offers a one-time in-app purchase. All purchases are processed and administered by Google Play under Google's own terms. We handle no payments and store no payment details.
Refunds are subject to Google Play's refund policy and to your statutory rights as a consumer. Refund requests should be directed to Google Play. Where a purchase unlocks features immediately upon payment, the statutory right of withdrawal for digital content may lapse once delivery has begun with your consent.
Purchased features are tied to the Google account used for the purchase and can be restored on that account.
You agree not to use the app in any way that is unlawful, that interferes with the normal operation of your device or other software, or that circumvents any technical limitation or licensing check in the app.
The app draws an overlay on top of other applications. You are responsible for using it sensibly — for example, not enabling a filter at an intensity that obscures information you need to see, and not using it in situations where reduced screen visibility could be unsafe.
The app is provided on an "as is" and "as available" basis. We may update, modify or discontinue the app or any feature at any time. Android versions, device manufacturers and system restrictions on overlays, background services and alarms may change and can affect how the app behaves; we cannot guarantee continued compatibility with every device or Android version.
To the fullest extent permitted by law, the app is provided without warranties of any kind, whether express or implied, including fitness for a particular purpose and uninterrupted or error-free operation.
We are not liable for any indirect or consequential loss, loss of data, or damage arising from use of or inability to use the app, including any missed schedule, failed alarm, or overlay behaviour caused by the operating system or device manufacturer.
Nothing in these terms limits liability for death or personal injury caused by negligence, for fraud, or for any liability that cannot be excluded under Dutch law. Your statutory rights as a consumer are unaffected.
Use of the app is also governed by our Privacy Policy, available at this site and in the app under Settings → About and legal.
You may stop using the app at any time by uninstalling it. This licence terminates automatically if you breach these terms. Uninstalling removes all locally stored settings.
We may update these terms occasionally. The current version is always available at this URL with a revised date at the top. Continued use of the app after an update constitutes acceptance of the revised terms.
These terms are governed by Dutch law. Disputes are subject to the jurisdiction of the competent courts in the Netherlands, without prejudice to any mandatory consumer protection rules of the country in which you reside.
E-mail: info@goudboom.nl
Goudboom Enterprise, Netherlands