Terms of use

Last updated: 13 May 2026

These terms of use (“Terms”) govern your use of the Undertint application and the undertint.app website (together, the “Service”), provided by Justin Stach (“we”, “us”, “our”), based in the United Kingdom. By using Undertint, you agree to be bound by these Terms. If you do not agree, please do not use the Service.

Use of the Service

We grant you a non-exclusive, non-transferable, revocable right to use Undertint for personal or commercial purposes, subject to these Terms.

You may not:

• Reverse engineer, decompile, or disassemble the application, except to the extent permitted by applicable law
• Redistribute, sublicence, or resell the application or its output in a way that competes with the Service
• Remove or alter any proprietary notices or labels
• Use the application in any way that violates applicable law

In-app purchases

Undertint Pro is a one-off, non-consumable in-app purchase offered through Apple’s App Store. The purchase unlocks two- and three-paint mix recipes within Undertint. There is no subscription and no recurring charge.

The purchase is tied to your Apple ID and is available on all iOS devices signed in to that Apple ID. Family Sharing is enabled, so a single purchase covers your Apple Family group at no additional cost.

Refunds for in-app purchases are handled by Apple. Requests can be made at reportaproblem.apple.com. Stach Ltd cannot process refunds directly.

Intellectual property

Undertint, including its design, code, algorithms, icons, and documentation, is the intellectual property of Justin Stach. All rights not expressly granted in these Terms are reserved. The colour mixing recipes and visual output you generate using Undertint belong to you — we claim no ownership or rights over your creative work.

Your data

Undertint processes your images locally on your device. We do not upload, store, or have access to the photos you use. Your sessions, palettes, and recipes are stored on your device. For full details of how we handle information, please see our privacy policy.

Availability

We do not guarantee that Undertint will be available, uninterrupted, or error-free at all times. We may modify or discontinue any part of the Service at any time, though we will make reasonable efforts to provide notice of significant changes.

Disclaimer of warranties

To the maximum extent permitted by law, Undertint is provided “as is” and “as available” without warranties of any kind, whether express or implied, including but not limited to implied warranties of merchantability, fitness for a particular purpose, and non-infringement.

Nothing in these Terms excludes or limits your statutory rights as a consumer under English law, including your rights under the Consumer Rights Act 2015. Digital content must be of satisfactory quality, fit for a particular purpose, and as described.

Limitation of liability

To the maximum extent permitted by applicable law:

• We shall not be liable for any indirect, incidental, special, consequential, or punitive damages, including but not limited to loss of data, loss of profits, or business interruption, arising out of or in connection with your use of Undertint.
• Our total aggregate liability to you for any claims arising out of or relating to these Terms or your use of Undertint shall not exceed the amount you paid for the Service (if any).

Nothing in these Terms excludes or limits our liability for death or personal injury caused by our negligence, fraud or fraudulent misrepresentation, or any other liability that cannot be excluded or limited under English law.

Changes to these Terms

We may update these Terms from time to time. Any changes will be posted on this page with an updated “last updated” date. Your continued use of Undertint after changes are posted constitutes your acceptance of the revised Terms.

Termination

We may terminate or suspend your access to Undertint if you breach these Terms. Upon termination, you must cease all use of the Service.

Termination does not affect any rights or obligations that accrued before the termination date. The sections on intellectual property, limitation of liability, and governing law survive termination.

Governing law and jurisdiction

These Terms are governed by and construed in accordance with the laws of England and Wales. Any disputes arising out of or in connection with these Terms shall be subject to the exclusive jurisdiction of the courts of England and Wales.

If you are a consumer, this does not affect any mandatory consumer protection laws that apply in your country of residence.

Entire agreement

These Terms, together with our privacy policy, constitute the entire agreement between you and us regarding your use of Undertint.

Contact

If you have any questions about these Terms, please contact us at:

Justin Stach
Email: hello@stach.ltd