Terms of Use

Updated 10 October 2026

These terms are an agreement between you and DC Math, Singapore ("we", "us"), which operates Tangent. By creating an account, joining a board or otherwise using Tangent you agree to them. If you do not agree, please do not use Tangent.

1. The service

Tangent is an online whiteboard for lessons: shared boards with live handwriting, attachments, calculators, chat and, on some boards, a built-in video call. It needs an internet connection. We may add, change or remove features.

2. Accounts and guests

You can sign in with Google or Apple, or join as a guest with a display name. Keep your sign-in secure and give accurate information. You are responsible for what happens under your account. A guest identity lives in one browser and is lost if its data is cleared.

3. Students and young users

If you are under 18, use Tangent only with the permission of a parent or guardian. Teachers and tutors who invite students are responsible for obtaining any consent the law requires and for supervising their own lessons.

4. Plans

Free. You may own up to 3 boards and can share a Google Meet link on each board.

Pro. You may own up to 50 boards, and the boards you own have a built-in video call that everyone on the board can join. Pro includes a monthly allowance of video participant-minutes (one person in a call for one minute), shown in your account menu. When the allowance is used up, the built-in call on your boards stops until the next calendar month; Google Meet links keep working.

People you invite do not need Pro to join your boards or your calls. If Pro ends, your boards remain, but you cannot create new ones while you own more than the Free limit, and the built-in video call stops working on your boards.

5. Payment, renewal and cancellation

Pro is a subscription billed in advance for each period at the price shown when you subscribe. It renews automatically until cancelled. You can cancel at any time and Pro continues until the end of the period already paid for. Except where the law requires otherwise, payments are not refunded for part of a period. We will give at least 30 days' notice of a price change, which applies from your next renewal.

6. Your content

You keep ownership of what you write and upload. You give us permission to store, copy and display it only as needed to run Tangent for you and the people on your boards. You are responsible for having the right to upload any material, including exam papers and textbook pages, and for what you share with others.

7. Acceptable use

Do not use Tangent to break the law, harass or harm others, share content that is unlawful or infringes someone's rights, upload malware, try to access boards or accounts that are not yours, guess room IDs, overload or disrupt the service, or resell it without our agreement. Do not record or share other people's video, audio or work without their permission.

Sexual, hateful, threatening, violent or abusive shared content is not allowed. Use Report in People, Chat or Attachments to alert Tangent moderation, or contact chiadenn@gmail.com. You can block participants in People and manage blocks in Account. We may remove reported content and suspend abusive accounts after review.

8. Board owners

The owner of a board decides who may draw, may clear content and may delete the board. Deleting a board removes it for everyone and cannot be undone.

9. Other services

Tangent relies on other providers, including Supabase, Vercel, Google, Apple, Daily and the calculator emulator from TestNav. Google Meet links open Google's own service. Their terms apply to your use of their services, and we are not responsible for them.

10. Availability and changes

We aim to keep Tangent running but do not promise it will be uninterrupted or error-free. Keep your own copies of important work; boards can be exported as PDF or PNG.

11. Suspension and closing accounts

You may stop using Tangent at any time and delete your account from the account menu; deletion is permanent. We may suspend or close an account that breaks these terms or puts other users or the service at risk. Where reasonable we will give notice first.

12. Disclaimers and liability

Tangent is provided "as is". To the extent the law allows, we exclude implied warranties, and we are not liable for indirect or consequential loss, lost data or lost profits. Our total liability to you for any claim is limited to the amount you paid us for Tangent in the 12 months before the claim, or S$50 if you paid nothing. Nothing in these terms limits liability that cannot be limited by law.

13. Privacy

Our Privacy Policy explains how personal data is handled.

14. Changes to these terms

We may update these terms. We will post the new version here and, for significant changes, tell signed-in users in the app or by email. Continuing to use Tangent after a change means you accept it.

15. Governing law

These terms are governed by the laws of Singapore, and the courts of Singapore have jurisdiction over any dispute.

16. Contact

chiadenn@gmail.com