Terms of Use

These terms apply to the Khrap&Kha app and website, published by 4Envelopes. By using the app you agree to them.

What the app is

Khrap&Kha is an educational app for learning basic Thai phrases. It is free to use. We may change, add or remove lessons and features.

Learning content

We try to keep phrases, translations, transliterations and audio accurate, but language learning material can contain mistakes, and transliteration and reading aids are only approximations of Thai pronunciation. Don’t rely on the app for medical, legal, safety-critical or emergency communication.

Pronunciation and tone scores

Scores are produced automatically (Microsoft Azure AI Speech and on-device pitch analysis). They are guidance for practice, not an assessment or certification, and may be affected by noise, microphone quality and accent.

Acceptable use

Use the app for personal learning. Don’t attempt to disrupt our servers, abuse the pronunciation service with automated or excessive requests, or copy and redistribute the content, audio or illustrations.

Intellectual property

The app, lessons, audio recordings, illustrations and design belong to 4Envelopes or its licensors. You get a personal, non-exclusive, non-transferable licence to use the app on your devices. If you downloaded the app from the App Store, Apple’s Standard End User License Agreement also applies.

Third-party services

The app uses Cloudflare to deliver content and run our server, and Microsoft Azure AI Speech for pronunciation scores. Their availability is outside our control.

No warranty and limitation of liability

The app is provided “as is” and “as available”. To the extent permitted by law, 4Envelopes is not liable for indirect or consequential losses arising from use of the app. Nothing in these terms limits rights you have under consumer protection law.

Changes and contact

We may update these terms; the date below shows the latest version. Questions: sergei@4envelopes.app.

Last updated: 2026-10-25