Terms of Service

Last Updated: September 19, 2026 · Version 1.0

These Terms of Service ("Terms") are entered into between Data Network Technology Lab ("DNT Group") and you, and govern your use of Efunction (the "Software"). These Terms are drafted with reference to the laws of the Hong Kong Special Administrative Region (HKSAR) and the EU General Data Protection Regulation (GDPR), taking into account multi-regional compliance requirements. By accessing or using the Software, or by registering an account, you acknowledge that you have read, understood and agreed to be bound by these Terms and the Software's Privacy Policy.

1. Acceptance of Terms

1.1 Please read these Terms carefully before using the Software. Your access to or use of the Software constitutes acceptance of these Terms. If you do not agree with any part of these Terms, you must stop using the Software immediately.

1.2 If you accept these Terms on behalf of a legal entity or other organisation, you represent that you are duly authorised to bind such entity to these Terms.

1.3 These Terms, together with the Privacy Policy, form the complete legal documentation of the Software. https://dnteam.top is the official website designated by DNT Group.

2. Description of the Service

2.1 The Software is a browser-based online function-plotting and mathematical visualisation tool. It supports Cartesian functions, parametric equations, polar curves and definite integrals, and offers analysis features such as derivatives, intersection search, function tables and parameter sliders. Rendering and numerical calculation are performed locally on your device by default.

2.2 The Software also offers an optional cloud-saving feature for schemes, which requires a registered and signed-in account. The processing of such scheme data is governed by the Software's Privacy Policy.

2.3 DNT Group may update the Software from time to time to add features or fix defects; the updated version is subject to these Terms and its applicable licence terms.

3. Eligibility and Consent

3.1 You must have the legal capacity to enter into these Terms. If you are a minor, you must use the Software under the supervision and with the consent of your guardian.

3.2 Any processing of personal data or scheme data is governed by the Software's Privacy Policy, to which you agree to comply.

4. Open Source Licence and Licence Grant

4.1 The source code of the Software is made available under the Efunction Source Code Licence and User Agreement. You may freely view, copy, modify and use the source code for personal, educational or commercial purposes, provided that the original copyright notice and licence terms are retained.

4.2 Subject to these Terms, DNT Group grants you a non-exclusive, non-transferable and revocable licence to install and use the Software on compatible devices.

4.3 Except as expressly permitted by these Terms or the open-source licence, you may not reverse engineer, decompile, disassemble, circumvent or bypass any technical protection measures of the source code without DNT Group's prior written consent.

5. Permitted Use

5.1 You may use the Software for personal study, teaching, research or commercial purposes that are lawful, in direct furtherance of your own mathematical plotting and visualisation needs.

5.2 You may modify and redistribute the Software in accordance with the open-source licence terms, provided that you attribute the source and retain the copyright and licence information.

6. Prohibited Use and Acceptable Use Policy

You agree not to:

Use the Software for any unlawful purpose or to infringe the rights of any third party;
Use the Software or its cloud-saving feature to upload, store or distribute any illegal, infringing, harmful or malicious content;
Attack, interfere with, scan, scrape or disrupt DNT Group or its related websites, servers or other infrastructure;
Use the Software in any way that may compromise the privacy, data security or public interest of others;
Violate any applicable laws and regulations of the jurisdictions where the Software and you are located.

7. Cloud Service and Account Security

7.1 The cloud-saving feature is optional. Once enabled, the scheme data you save is transmitted over the network and stored on servers designated by DNT Group, in order to synchronise and restore your plotting schemes across devices.

7.2 You are responsible for safeguarding your account credentials (including your login identifier and password) and for all activity under your account. If you become aware of any unauthorised use of your account, you must notify DNT Group immediately.

7.3 You shall not use the cloud service to store or transmit any illegal or infringing content, nor abuse, interfere with, or access the relevant services beyond the scope agreed.

8. Third-Party Components and Links

8.1 The Software may load third-party open-source libraries or resources via CDNs (for example, mathematical formula input and rendering components); their use is governed by their respective licence terms.

8.2 The Software may open links to official websites, documentation or other third-party pages in your system browser. DNT Group is not responsible for the content, privacy practices or availability of third-party websites.

9. Feedback and Contributions

9.1 If you submit suggestions, source code or bug reports to DNT Group, you grant DNT Group a perpetual, royalty-free, sub-licensable licence to use, modify and distribute such feedback, except for any personal data contained therein.

10. Intellectual Property

10.1 Except for content you submit and the function schemes you create yourself, the intellectual property rights in the Software, including its source code, documentation, interface design, trademarks, logos and related materials, belong to DNT Group or the respective right holders and are protected by HKSAR and international intellectual property laws.

10.2 Nothing in these Terms grants you any right to use any trademark, trade name or logo.

11. Disclaimer of Warranties

11.1 The Software is provided "as is" and "as available". To the maximum extent permitted by applicable law, DNT Group makes no express or implied warranties regarding merchantability, fitness for a particular purpose, security, accuracy or non-infringement.

11.2 You acknowledge and agree that the accuracy of mathematical plots and numerical results depends on the input expressions, rendering engine, browser environment and device performance. The Software makes no guarantee as to results used for professional, examination, engineering or business decisions, and does not constitute professional advice of any kind.

12. Limitation of Liability

12.1 To the maximum extent permitted by applicable law, DNT Group and its affiliates and contributors shall not be liable for any indirect, incidental, special, punitive or consequential damages (including but not limited to loss of data, loss of schemes, loss of profits or business interruption) arising out of or in connection with the use or inability to use the Software, even if advised of the possibility of such damages.

12.2 DNT Group is not responsible for loss of scheme data caused by your forgetting your password, unauthorised use of your account, or failure to use the local backup function in a timely manner. We recommend that you periodically export your schemes as local backup files.

13. Indemnification

13.1 You agree to indemnify and hold harmless DNT Group, its affiliates and contributors from any claims, damages, costs or liabilities arising out of your breach of these Terms, applicable law or infringement of third-party rights.

14. Privacy and Personal Data

14.1 The processing of personal data (including collection, use, retention, security and access rights) is governed by the Privacy Policy, and you agree that DNT Group processes relevant data in accordance therewith.

15. Term and Termination

15.1 These Terms take effect when you begin using the Software and remain in effect until terminated in accordance with this section.

15.2 If you breach these Terms, DNT Group may terminate your licence and cloud service at its sole discretion. Termination shall not affect rights and obligations accrued prior to termination or provisions that by their nature should survive.

15.3 You may stop using the Software at any time and may request deletion of your account and cloud scheme data through the functions provided in the Software.

16. Governing Law and Jurisdiction

16.1 These Terms are governed by, and construed in accordance with, the laws of the HKSAR (without regard to its conflict-of-laws rules).

16.2 Any dispute arising out of or in connection with these Terms shall first be resolved through good-faith negotiation; failing which, the courts of the HKSAR shall have non-exclusive jurisdiction. Nothing herein limits the mandatory protections available to consumers under the law of their place of residence.

17. Dispute Resolution and Mediation

17.1 The parties agree that, prior to litigation, disputes may, with mutual written consent, be submitted to mediation, arbitration or other alternative dispute resolution mechanisms to reduce enforcement costs.

18. Severability and Entire Agreement

18.1 If any provision of these Terms is held invalid or unenforceable, the remaining provisions shall remain in full force and effect, and the invalid provision shall be construed to the maximum extent permitted by law.

18.2 These Terms, together with the Privacy Policy, constitute the entire agreement between the parties regarding use of the Software and supersede all prior oral or written agreements.

18.3 DNT Group's failure to exercise any right in respect of a single breach shall not constitute a waiver of any breach.

19. Changes to Terms

19.1 DNT Group reserves the right to amend these Terms at any time. Upon any change, DNT Group will post the updated version with a new effective date on the official website or notify you in-app.

19.2 It is your responsibility to review these Terms regularly; continued use of the Software after any change becomes effective constitutes acceptance of the updated Terms. For material changes, DNT Group will use reasonable efforts to notify you in advance.

20. Language and Text

20.1 These Terms are provided in Simplified Chinese, English and Traditional Chinese. The texts are of equal effect; in case of any inconsistency, the interpretation more favourable to you shall prevail.

21. Contact Information

If you have any questions, complaints or suggestions regarding these Terms or the Software, please contact us via the official website https://dnteam.top or in-app contact channels. For personal-data privacy matters, you may submit a data access or correction request in accordance with the Privacy Policy.