Last updated: 9 October 2026
These Terms of Use (collectively, the "Terms") together with all the documents referred to in it constitute a legally binding agreement made between you as a natural person ("you", "your" or "user") and HEYKU STUDIO ("we," "us" or "our"), concerning your access to and use of HanziLab (also published under the project name "EasyChinese"; collectively — the app, software), and the content available via the app, the computer files stored on our servers, and all related services, features, and tools.
All the documents that relate to the app are hereby expressly incorporated herein by reference. Please read these Terms carefully before using the app.
It is important that you read and understand these Terms as by using the app you indicate that you have read, understood, agreed, and accepted the Terms. By using the app, you agree to abide by these Terms.
If you do not agree with (do not accept) these Terms, or if you do not agree with at least one of the provisions of these Terms, you are not authorized to, and you may not access and/or use the app, and you must promptly discontinue accessing and/or using the app.
We reserve the right, at our sole discretion, to make changes or modifications to these Terms at any time and for any reason. We will keep you informed about any changes by updating these Terms and you waive any right to receive specific notice of each such change. It is your responsibility to periodically review these Terms to stay informed of updates. You will be subject to, and will be deemed to be aware of and to have accepted, the changes in any revised Terms by your continued use of the app after the date such revised Terms are posted.
To access and use HanziLab, you must be at least four (4) years of age or older, in accordance with the app's App Store age rating. If you are a minor in your jurisdiction, you may only use the app under the supervision of, and with the consent of, a parent or legal guardian, and your parent or legal guardian is responsible for your use of the app.
By using the app, you affirm that you meet the age requirements and are fully able and competent to enter into the terms, conditions, obligations, affirmations, representations, and warranties set forth in these Terms, and to abide by and comply with these Terms.
HanziLab is developed for general education and language-learning purposes. It helps you learn Mandarin Chinese through HSK-aligned vocabulary, pinyin and tone practice, Chinese character handwriting, pronunciation drills, dictionary lookup, reading practice, and spaced-repetition review. The app is intended only for your personal, non-commercial use. You agree not to use the app for any illegal, inappropriate, or unauthorized purpose or activity.
The app is a study aid, not a substitute for a certified language instructor, a HSK proficiency test, or any official certification. We make no representation that use of the app will result in a specific HSK score, grade, test outcome, academic credit, or professional qualification.
You represent and warrant that you have all necessary rights, permissions, and consents to any text, voice recordings, or other content you create, submit, or import through the app, including any content containing another person's likeness, name, trademark, or copyrighted material.
You are solely responsible for the content you create with the app and for any consequences arising from using, sharing, or exporting such content.
Your privacy is very important to us. Accordingly, we have developed the Privacy Policy in order for you to understand how we handle information, including personal data.
Your use of the app is subject to our Privacy Policy, which explains what data is collected, how it is processed, and how it may be handled by us and our service providers (including Apple, Google Firebase, Microsoft Azure Speech, Adjust, OneSignal, and Intercom).
Access to and/or use of the app are subject to the Privacy Policy. By accessing and/or using the app, you are deemed to have accepted the Privacy Policy, and in particular, you are deemed to have acknowledged the ways we handle your information as well as the appropriate legal grounds for processing described in the Privacy Policy. We reserve the right to amend the Privacy Policy from time to time. If you disagree with any part of the Privacy Policy, you must immediately stop accessing and/or using the app. Please read our Privacy Policy carefully.
All intellectual property rights in the app, including but not limited to copyrights, trademarks, trade secrets, and patents, as well as the app's source code, design, user interface, HSK curriculum compilation, dictionary data compilation, example sentences, audio samples, voice models, flashcard decks, and all derivative works (collectively, "Intellectual Property"), are owned by HEYKU STUDIO or its licensors.
We grant you a limited, non-exclusive, non-transferable, non-sublicensable, revocable license to access and use the app for your personal, non-commercial purposes strictly in accordance with these Terms.
You agree not to:
Sell, distribute, sublicense, or commercially exploit any content from the app (including HSK vocabulary lists, example sentences, dictionary entries, audio samples, voice models, flashcard decks, or compiled reading passages).
Copy, reproduce, modify, create derivative works of, publicly display, publicly perform, republish, download, store, or transmit any of the templates, fonts, backgrounds, audio samples, voice models, or other material provided by the app, except as incidentally necessary to access and use the app for its intended personal study purposes.
Reverse engineer, decompile, or disassemble the app or attempt to derive the source code (except to the extent such restriction is prohibited by applicable law).
Scrape, bulk-export, or re-publish the app's content (including HSK word lists, dictionary data, example sentences, and audio) through automated means.
Delete or alter any copyright, trademark, or other proprietary rights notices from copies of materials from the app.
Use the app to train, fine-tune, or evaluate any artificial-intelligence or machine-learning model without our prior written permission.
Redistribute or repackage any part of the app's content in a way that misrepresents it as being provided by, endorsed by, or affiliated with us.
Any use of the app not expressly permitted by these Terms is a breach of these Terms and may violate copyright, trademark, and other laws.
Third-party content and attributions. The app bundles or draws on open-source and third-party components, which may be subject to their own licenses (for example, CC-licensed dictionary data, open-source voice models for Sherpa-ONNX offline TTS/ASR, Google ML Kit Digital Ink Recognition, and other open-source libraries). The relevant licenses, attributions, and credits are listed in the app's attribution page. Your use of those components is additionally subject to their respective licenses.
You agree not to use the app in any manner that:
Is unlawful, illegal, or unauthorized.
Is defamatory, obscene, indecent, abusive, offensive, harassing, violent, hateful, inflammatory, or otherwise objectionable.
Infringes any patent, trademark, trade secret, copyright, or other intellectual property or other rights of any other person.
Violates the legal rights (including the rights of publicity and privacy) of others or contains any material that could give rise to any civil or criminal liability under applicable laws or regulations.
Promotes any illegal activity, or advocates, promotes, or assists any unlawful act.
Involves commercial activities or sales, such as contests, sweepstakes, resale of our content, teaching for commercial fees using our content as the primary teaching material, or advertising, without our prior written consent.
Gives the impression that it emanates from or is endorsed by us, by any official Chinese-language certification body (including Hanban/CLEC, the HSK testing authority, or any affiliated institution), or any other person or entity, if this is not the case.
Interferes with or disrupts the integrity or performance of the app or the data contained therein.
Attempts to gain unauthorized access to the app, our back-end servers, or any related systems or networks.
Introduces viruses, Trojan horses, worms, logic bombs, or other material that is malicious or technologically harmful.
Uses automated means (bots, scrapers, headless clients) to interact with the app's back-end or to bulk-export app content.
Submits abusive, misleading, or spam content through the in-app support chat (Intercom) or through our support email.
We reserve the right to take appropriate legal action against any unauthorized use of our Intellectual Property Rights or any prohibited conduct.
All disputes arising from the usage of the app shall be governed by and construed in accordance with the laws of Singapore, and shall be submitted to the sole jurisdiction of the Singapore International Arbitration Centre.
The app is provided on an "as is" and "as available" basis, without any warranties of any kind, either express or implied.
We do not guarantee the accuracy, reliability, completeness, or timeliness of any content or data provided through the app, including HSK word lists, example sentences, dictionary definitions, pinyin, tone marks, grammar notes, radical decompositions, stroke orders, reading passages, pronunciation scores, or handwriting-recognition results. The app's HSK vocabulary is based on publicly available HSK syllabi; it is not an official product of, nor endorsed by, any HSK testing authority.
We disclaim all warranties, whether express or implied, including but not limited to implied warranties of merchantability, fitness for a particular purpose, title, and non-infringement.
We are not responsible for any errors or omissions, or for any results obtained from the use of the app, including — without limitation — exam outcomes, test scores, academic credit, or professional qualifications.
Pronunciation-scoring disclaimer. Pronunciation scores produced by the app (whether through the offline Sherpa-ONNX engine or the online Microsoft Azure Speech Pronunciation Assessment engine) are automated estimates. They are not a substitute for a human teacher's assessment and may be affected by microphone quality, ambient noise, accent, dialect, speaking rate, and other factors.
Handwriting-recognition disclaimer. Chinese handwriting recognition is powered by Google ML Kit Digital Ink Recognition and runs on-device. Recognition results are automated estimates and may be incorrect, particularly for non-standard, cursive, or stylized handwriting.
Your reliance on any information obtained through the app is solely at your own risk.
Access to the app requires a compatible iPhone or iPad (iOS 17 or later). Certain features — such as in-app support (Intercom), pronunciation scoring in online mode (Microsoft Azure Speech), remote notifications (FCM / OneSignal), download of optional voice-model bundles, and server-side preferences sync — require an active internet connection. We do not guarantee that the app will be compatible with all devices or software.
We do not warrant that the app will be uninterrupted, timely, secure, or error-free. The availability of the app may be affected by factors outside our control, such as internet connectivity issues, App Store availability, or third-party service-provider performance (for example, outages of Firebase, Microsoft Azure Speech, Adjust, OneSignal, or Intercom).
We may update the content on the app from time to time, but its content is not necessarily complete or up-to-date. Any of the material on the app may be out of date at any given time, and we are under no obligation to update such material. We may add new features, change, or remove existing features, or modify the app at any time without notice. We may also suspend or terminate access to the app, or any part thereof, at our discretion, for any reason, including for violation of these Terms.
You are responsible for ensuring that any information you provide to us through the app (for example, in the in-app support chat) is accurate, complete, and current.
The current release of HanziLab is provided free of charge, with no in-app purchases, no subscriptions, and no advertising.
We reserve the right to introduce paid features, subscriptions, consumable purchases, or advertising in a future release. If and when we do so, pricing, billing cycles, cancellation, refund procedures, and any applicable advertising disclosures will be presented to you within the app at the point of purchase and reflected in an updated version of these Terms and of our Privacy Policy before the change takes effect. Your continued use of the app after such changes constitutes your acceptance of the updated Terms.
If paid features are introduced in the future, except where required by applicable law, all purchases will be processed by the Apple App Store, will be governed by the App Store's refund procedures, and will be non-refundable by us for partial subscription periods, partial use, unused time, failure to cancel before renewal, dissatisfaction with subjective expectations (including subjective learning progress or test outcomes), or consumed credits.
The app may link you to other sites on the internet and contracted third parties to provide you certain services (for example, Firebase for analytics and push, Microsoft Azure Speech for pronunciation scoring, Adjust for attribution, OneSignal for push, Intercom for support, and any linked support, dictionary, or attribution pages). We have no control over and accept no responsibility for the content of any website or mobile application to which a link from the app exists (unless we are the provider of those linked websites or mobile applications). Such linked websites and mobile applications are provided "as is" for your convenience only with no warranty, express or implied, for the information provided within them.
You acknowledge sole responsibility for and assume all risk arising from your use of any third-party websites or resources.
If you have any queries, concerns, or complaints about such third-party websites or mobile applications (including, but not limited to, queries, concerns, or complaints relating to products, orders for products, faulty products, and refunds) you must direct them to the operator of that third-party website or mobile application.
HanziLab runs primarily on your device. Spaced-repetition scheduling, flashcard review, dictionary lookup, handwriting recognition, offline text-to-speech, offline pronunciation scoring, and your personal review history are performed locally. Certain features rely on device hardware, permissions you grant to the app, and (where applicable) network services:
Microphone (Speak drill): Used solely to capture your spoken drill answer. If the offline engine is active, audio is processed entirely on-device by Sherpa-ONNX. If the online engine is active, the audio sample is transmitted to Microsoft Azure Speech for pronunciation scoring and then discarded. The microphone is used only while a Speak drill is active.
Handwriting (Chinese character drills): Powered by Google ML Kit Digital Ink Recognition, which runs entirely on your device. Strokes are not transmitted off-device.
Local notifications: Scheduled by iOS when you enable the daily reminder in Settings. You can disable them at any time in iOS Settings.
Remote notifications (FCM / OneSignal): Delivered through Apple Push Notification service when we send a re-engagement or product notification. You can disable them at any time in iOS Settings.
Background download sessions: Used to download optional voice-model bundles (Chen Wang native-speaker audio, Sherpa VITS text-to-speech, Sherpa Zipformer CTC ASR) when you tap "Download" in Settings. Only the files you explicitly request are downloaded.
You can revoke any of these permissions at any time in the iOS Settings app; some features may then become unavailable (for example, Speak drills require the microphone, and reminders require notification permission).
IN NO EVENT SHALL WE BE LIABLE FOR DAMAGES OF ANY TYPE, WHETHER DIRECT OR INDIRECT, ARISING OUT OF OR IN ANY WAY RELATED TO THE APP AND SERVICES PROVIDED BY THE APP.
WE ARE NOT LIABLE FOR ANY CONSEQUENCES BASED ON INTERPRETATIONS OR DECISIONS MADE BY USERS BASED ON INFORMATION OR DATA PROVIDED BY THE APP (INCLUDING, BUT NOT LIMITED TO, HSK WORD LISTS, DICTIONARY DEFINITIONS, EXAMPLE SENTENCES, PINYIN, TONE MARKS, GRAMMAR NOTES, STROKE ORDERS, PRONUNCIATION SCORES, HANDWRITING-RECOGNITION RESULTS, OR SPACED-REPETITION SCHEDULING). WE SHALL NOT BE LIABLE UNDER ANY CIRCUMSTANCES FOR ANY SPECIAL, CONSEQUENTIAL, INCIDENTAL, EXEMPLARY, OR PUNITIVE DAMAGES, OR LOSS OF PROFIT OR REVENUES, EVEN IF WE HAVE BEEN SPECIFICALLY ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. WE SHALL NOT BE LIABLE UNDER ANY CIRCUMSTANCES FOR DAMAGES ARISING OUT OF OR IN ANY WAY RELATED TO PRODUCTS, SERVICES, AND/OR INFORMATION OFFERED OR PROVIDED BY ANY THIRD PARTIES AND ACCESSED THROUGH THE APP OR BY ANY OTHER MEANS. YOU ALSO SPECIFICALLY ACKNOWLEDGE THAT WE ARE NOT LIABLE FOR COSTS OR DAMAGES ARISING OUT OF PRIVATE OR GOVERNMENTAL LEGAL ACTIONS RELATED TO YOUR USE OF THE APP AND ITS SERVICES IN ANY COUNTRY.
HanziLab does not require you to create an email-based online account. Your saved deck, review history, mined vocabulary, and preferences are stored locally on your device. A pseudonymous device identifier is stored in the iOS Keychain to associate server-side preferences with your installation.
You may delete your learning data at any time from within the app (for example, by resetting onboarding, deleting mined entries, or by removing downloaded voice bundles in Settings). To remove all app data, delete the app from your device; this will remove all locally stored decks, review history, preferences, downloaded voice bundles, and any locally cached content. Any server-side data linked to your pseudonymous installation identifier will be dissociated or deleted in accordance with our Privacy Policy.
If you wish to request deletion of the limited server-side data associated with your installation (for example, anonymous telemetry), contact us at heyku.studio@gmail.com. We will process your request in accordance with our Privacy Policy and applicable laws. Please note that some data may be retained for a limited period as required by law or for legitimate business purposes.
You agree to defend, indemnify, and hold harmless HEYKU STUDIO, its affiliates, licensors, and service providers, and its and their respective officers, directors, employees, contractors, agents, licensors, suppliers, successors, and assigns from and against any claims, liabilities, damages, judgments, awards, losses, costs, expenses, or fees (including reasonable attorneys' fees) arising out of or relating to your violation of these Terms or your use of the app, including, but not limited to, any content you submit (for example, through the in-app support chat), any use of the app's content, services, and products other than as expressly authorized in these Terms, or your use of any information obtained from the app.
Without limiting the foregoing, you shall be solely responsible for obtaining all necessary permissions and consents relating to any third-party content, likeness, trademark, or personal data used with the app.
If at any time any provision of these Terms is or becomes illegal, invalid, or unenforceable in any respect, that provision shall be more narrowly construed so that it becomes legal, valid, and enforceable or, if this is not possible, deleted. The other terms of these Terms shall continue to apply with full force and effect.
You shall not assign or transfer or purport to assign or transfer the contract between you and us to any other person.
We reserve the right to respond to your requests, questions, commentaries, or suggestions. For these purposes you can reach us at:
HEYKU STUDIO
Email: heyku.studio@gmail.com