Terms of Service

Last updated: September 14, 2026

These Terms of Service (the "Terms") are a binding agreement between you and Mathhead, Inc., a Delaware corporation ("Mathhead", "we", "us", or "our"), governing your access to and use of EulerVertex, our AI-assisted platform for university-level mathematics at eulervertex.com, together with all related content, features, and applications (the "Service").

Please read Section 19 carefully. It requires most disputes to be resolved by individual binding arbitration and waives your right to participate in a class action. You may opt out of arbitration within 30 days.

1. Acceptance of These Terms

By creating an account, accessing, or using the Service, you agree to these Terms and to our Privacy Policy and Refund & Cancellation Policy, each incorporated here by reference. If you do not agree, do not use the Service.

If you use the Service on behalf of an organization, you represent that you have authority to bind that organization, and "you" includes it.

2. Who We Are

The Service is operated by Mathhead, Inc., a Delaware corporation.

  • Company: Mathhead, Inc.
  • Postal address: 1020 Florence Lane, #13, Menlo Park, CA, 94025, USA
  • Contact: service@eulervertex.com

3. Eligibility and Age Requirements

You must be at least 13 years old to use the Service. The Service is designed for university-level learners and educators.

You must be at least 18 years old, and of legal age to form a binding contract, to purchase a subscription or credits. If you are between 13 and 18, you may use the free portions of the Service only with the consent and supervision of a parent or legal guardian, who agrees to be bound by these Terms on your behalf.

By using the Service you represent that you meet these requirements, that you are not barred from using the Service under applicable law, and that you are not located in a country subject to a U.S. government embargo.

4. Accounts, Roles, and Security

Registration. You must provide an accurate email address and keep your account information current. One person may hold one account; do not share an account or transfer it to anyone else.

Security. You are responsible for safeguarding your password and for all activity that occurs under your account. Notify us immediately at service@eulervertex.com of any unauthorized use. We are not liable for losses arising from your failure to keep your credentials secure.

Roles. Accounts carry a role that determines what you can do. New accounts are students. Elevated roles — researcher, instructor, professional — and capabilities such as moderator or editor may be granted at our discretion following a role request in which you describe your background and qualifications.

You agree that any statements you make in a role request are truthful. Roles are granted on the basis of those statements, and elevated roles allow you to publish content that other users will rely on. We may verify, decline, suspend, or revoke any role or capability at any time, with or without notice, including where we believe a request contained a material misstatement.

5. Subscriptions, Credits, and Billing

Plans. We offer paid subscriptions and may offer prepaid credit packs. Current plans, prices, and what each includes are shown on our pricing and subscribe pages at the time of purchase. Those pages form part of these Terms.

Payment processing. Payments are processed by Stripe, Inc. By purchasing, you also agree to Stripe's terms and authorize us and Stripe to charge your payment method. You represent that you are authorized to use the payment method you provide. We do not store your full card details.

Automatic renewal. Subscriptions renew automatically at the end of each billing period — monthly or annual, as selected — and your payment method will be charged the then-current price for a further period, until you cancel. We will present the renewal terms clearly before you purchase.

Cancelling. You may cancel at any time. Cancellation stops future renewals; it takes effect at the end of your current paid period, and you keep access until then. See the Refund & Cancellation Policy for how to cancel and when refunds are available.

Credits. Where offered, credits are consumed by usage of certain features. Credits have no cash value, are not legal tender, cannot be transferred or exchanged between accounts, and do not expire. We may adjust how many credits a given action consumes on reasonable notice.

Weekly allowance refresh. Pro subscribers may buy a one-time refresh, at the price shown at purchase, that resets the current week's usage allowance to zero. It does not change your regular weekly reset date, and it is subject to the Refund & Cancellation Policy.

Price changes. We may change prices. Changes to the recurring price of an existing subscription will not take effect until your next billing period, and we will give you at least 30 days' notice by email so you can cancel first. Continuing after the change takes effect means you accept the new price.

Taxes. Prices exclude taxes unless stated. You are responsible for any sales, use, VAT, GST, or similar taxes, which we may collect and remit where required.

Failed payments. If a charge fails, we may retry it. If payment remains unresolved, we may suspend or downgrade your access to paid features until the balance is settled. Free features remain available.

Refunds. Refunds are governed by the Refund & Cancellation Policy.

6. Access Tiers and Free Content

Content on the Service is offered in tiers. Some is open to everyone including signed-out visitors; some requires an active paid subscription; and some is restricted to users we have specifically granted access. Locked content may still appear in search results and listings as a title-and-metadata preview.

We may change which content sits in which tier. We will not move content you have already paid specifically to access out of your reach during the period you paid for. Free content may be added, changed, or withdrawn at any time.

7. Acceptable Use

You agree not to:

  • break the law, infringe anyone's intellectual property or privacy, or help anyone else do either;
  • post content that is harassing, defamatory, hateful, threatening, sexually explicit, or that targets or endangers any person;
  • impersonate anyone, misrepresent your affiliation, qualifications, or role, or create an account for someone else without authorization;
  • upload malware, attempt to gain unauthorized access to any account, system, or data, probe or test the security of the Service, or interfere with its operation;
  • use the code-execution feature to attack any system, mine cryptocurrency, exfiltrate data, or circumvent any limit;
  • scrape, crawl, or bulk-download content, or use automated means to access the Service, except as permitted by our robots.txt;
  • circumvent, disable, or attempt to defeat any paywall, access tier, rate limit, or access control, or share paid content with people who have not paid for it;
  • resell, sublicense, or commercially redistribute the Service or its content without our written permission;
  • use the Service or its outputs to train, fine-tune, or evaluate a machine-learning model, or to build a competing product;
  • submit deliberately misleading content, manipulate votes, ratings, or Elo scores, or create multiple accounts to do so.

We may investigate suspected violations and take any action we consider appropriate, including removing content, restricting features, and suspending or terminating accounts.

8. Academic Integrity

You are responsible for using the Service in a way that complies with the academic integrity rules of your institution, your course, and your instructor. Those rules vary, and they take precedence over anything the Service allows you to do technically.

EulerVertex provides AI explanations, worked solutions, and community solutions. Submitting this material as your own work in a graded context may constitute academic misconduct at your institution. Some instructors permit AI assistance, some restrict it, and some prohibit it entirely. It is your responsibility to know which applies to you and to ask your instructor if you are unsure.

We are not responsible for any academic penalty, disciplinary action, or other consequence arising from your use of the Service. We do not act as an arbiter of any institution's honor code, and we have no obligation to intervene in any academic dispute.

Do not use the Service to complete an assessment you have been told to complete unaided, to solicit answers to a live exam, or to help another user do either.

9. Classes

For everyone. Classes are created and run by individual users, not by institutions and not by us. We do not verify that a class corresponds to a real course, or that its instructor holds any position at any institution. Joining a class means the instructors and teaching assistants of that class can see your work and progress within it, as described in the Privacy Policy. Note that your email address forms part of your profile and is visible to other signed-in users generally, not only to class staff — see Section 4 of the Privacy Policy, and choose the address you register with accordingly.

For instructors. If you create or run a class, you are responsible for how you use the personal information of your members, for the accuracy of what you publish to them, and for complying with any policies of your institution that apply to you. Do not invite people who have not agreed to be invited, and do not use class features to collect information you are not entitled to collect. You must not use rosters or member email addresses for anything other than running that class.

Invitations. If you invite someone by email, you confirm you have a legitimate reason to contact that person at that address.

10. Your Content

You keep ownership. You retain all rights you already hold in the content you create on the Service — discussion posts, comments, solutions, and any nodes, facets, pages, courses, curricula, problems, or problem lists you author ("Your Content"). These Terms do not transfer ownership to us.

Licence to us. You grant Mathhead a worldwide, non-exclusive, royalty-free, sublicensable licence to host, store, reproduce, adapt, format, display, and distribute Your Content solely to operate, provide, secure, and improve the Service and to promote it in a manner consistent with your privacy settings. This licence lasts as long as we host Your Content and ends when it is removed, except as described in "After removal" below.

Personal versus published content. Content you save with personal status is visible only to you and is not licensed to other users. Content you publish is different, and you should understand what publishing means before you do it.

Licence to other users. When you publish content on the Service, you grant every other user a worldwide, non-exclusive, royalty-free licence to view, use, copy, adapt, and build upon that content within the Service. The Service includes features that let other users copy your published content into their own collections and modify their copy. This is intentional — it is how shared material is reused and improved — but it means published content will be copied and altered by people you do not know, and you cannot recall those copies. Publish only content you are willing to share on these terms.

Attribution. Authorship is recorded and, for published content, displayed. Contributions to collaboratively edited material are recorded in its revision history.

After removal. If you delete published content, copies other users have already made, and contributions others have built upon, may remain on the Service. We may also retain backup copies for a limited period, and retain content where required for legal, safety, or moderation reasons.

Your responsibility. You represent that you own or have the necessary rights to Your Content, and that it does not infringe anyone's rights or break any law. Do not upload content you do not have the right to share — including textbook problems, solution manuals, exam papers, or other copyrighted material belonging to someone else.

Feedback. If you send us suggestions or feedback, you grant us an unrestricted, perpetual, irrevocable right to use it without obligation or compensation to you.

Moderation. We may, but are not obliged to, review, moderate, remove, or restrict any content. We are not responsible for content posted by users, and content published by users does not represent our views.

11. Our Content and Intellectual Property

The Service — including its software, design, interface, branding, the EulerVertex name and logo, and the curated content library and knowledge graph we create — is owned by Mathhead or its licensors and is protected by intellectual property law.

Your licence. Subject to these Terms and to any applicable access tier, we grant you a limited, personal, non-exclusive, non-transferable, revocable licence to access and use the Service and its content for your own study, teaching, or research. All rights not expressly granted are reserved.

You may not copy, redistribute, publish, sell, sublicense, or create derivative works from our content outside the Service, remove proprietary notices, reverse-engineer the Service, or use our trademarks without written permission.

Third-party and open-licensed content. Some content is derived from or based on third-party and openly licensed material. Where a third-party licence applies, that licence governs that material and we identify it where practicable. Nothing in these Terms limits rights you hold under an open licence.

Copyright complaints. If you believe content on the Service infringes your copyright, email service@eulervertex.com with: identification of the work; identification of the material and where it is located; your contact details; a statement that you believe in good faith the use is not authorized; a statement, under penalty of perjury, that your notice is accurate and that you are authorized to act; and your signature. We will investigate and may remove the material and terminate repeat infringers.

12. AI Features — Important Disclaimer

The Service includes AI-generated explanations, worked solutions, generated practice problems, an AI tutor, and automated grading (together, "AI Features"). Read this section carefully.

AI output may be wrong. AI Features are powered by large language models, which produce plausible but sometimes incorrect output. Explanations may contain mathematical errors. Worked solutions may reach wrong answers or use invalid reasoning. Generated problems may be ill-posed, unsolvable, or paired with an incorrect answer key. Definitions, theorems, and statements of results may be misstated. This happens routinely, not rarely.

Automated grading may be wrong. Answers are graded automatically. Grading may mark a correct answer incorrect, or an incorrect answer correct. Elo ratings, progress indicators, and any other metric derived from grading are approximations and carry the same errors forward. Do not treat them as an authoritative measure of your ability or a problem's difficulty.

No warranty of accuracy. We provide AI Features "as is", and we make no representation or warranty that any output is accurate, complete, current, reliable, or fit for any purpose.

Not a substitute for instruction. The Service is a study aid. It is not a substitute for instruction from a qualified educator, for a textbook, for your institution's curriculum, or for professional advice of any kind. Verify anything important against an authoritative source before relying on it — especially for graded work, research, publication, or anything else with consequences.

Third-party processing. Your prompts and the surrounding content context are sent to Google's Vertex AI to generate a response, as described in the Privacy Policy. Requests may be served from a Google data centre outside the United States. Do not enter sensitive personal information, credentials, or confidential material into AI Features.

Usage limits. AI Features consume model capacity, and we record how much each account uses. We may set fair-use limits, rate-limit or temporarily suspend access to AI Features for an account whose usage is disproportionate or automated, and require an active subscription or credits for continued access.

Your responsibility. You are responsible for how you use AI output and for verifying it. To the fullest extent permitted by law, we are not liable for any loss arising from your reliance on AI output, including academic, professional, financial, or reputational harm.

13. Third-Party Services

The Service integrates third-party services, including payment processing, email delivery, AI providers, hosting, and a sandboxed code-execution service. We do not control them and are not responsible for their availability, performance, or acts. Their terms may apply to your use of them. Links to third-party sites are not endorsements.

14. Availability and Changes to the Service

We may modify, suspend, or discontinue any part of the Service at any time. We may impose limits on features or storage, or restrict access to parts of the Service, without notice or liability.

The Service is provided without any guarantee of uptime. We do not commit to a service level, and maintenance, updates, or outages may make the Service unavailable. If we discontinue a paid feature you are currently paying for, we will provide a pro-rata refund for the unused portion of your paid period as your sole remedy.

Beta features. We may label features as beta, preview, or experimental. These are provided as-is, may be changed or withdrawn without notice, and may not work correctly.

15. Suspension and Termination

By you. You may stop using the Service at any time. You can delete your account yourself from your dashboard — deletion is immediate and irreversible, and what is erased and what is reattributed to an anonymous placeholder is described in Section 9 of the Privacy Policy. You may also email service@eulervertex.com and we will do it for you. Cancelling a subscription is covered by the Refund & Cancellation Policy.

By us. We may suspend or terminate your account or access, with or without notice, if we reasonably believe you have breached these Terms, if your use creates risk or legal exposure for us or another user, if required by law, or if we discontinue the Service.

Where practicable and lawful, we will give you notice and an opportunity to address the problem before terminating, except where the breach is serious, repeated, or where doing so would create risk to others or to the Service.

Effect. On termination, your licence to use the Service ends immediately and you lose access to paid content. Sections 10 (as to licences granted before termination), 11, 12, 16, 17, 18, 19, 20, and 22 survive. If we terminate your account without cause, we will refund the unused portion of your current paid period. If we terminate for breach, no refund is due.

16. Disclaimers

THE SERVICE AND ALL CONTENT ARE PROVIDED "AS IS" AND "AS AVAILABLE", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. To the fullest extent permitted by law, we disclaim all warranties, including implied warranties of merchantability, fitness for a particular purpose, title, non-infringement, and any warranty arising from course of dealing or usage of trade.

We do not warrant that the Service will be uninterrupted, secure, timely, or error-free; that defects will be corrected; that the Service is free of harmful components; or that any content, including mathematical content, AI output, automated grading, or user-submitted material, is accurate, complete, or reliable.

No advice or information you obtain from us or through the Service creates any warranty not expressly stated here.

Some jurisdictions do not allow the exclusion of implied warranties, so some of the above may not apply to you. Nothing in these Terms excludes or limits any right you have under mandatory consumer protection law in your country of residence.

17. Limitation of Liability

TO THE FULLEST EXTENT PERMITTED BY LAW:

Mathhead, its officers, directors, employees, agents, and licensors will not be liable for any indirect, incidental, special, consequential, exemplary, or punitive damages, or for any loss of profits, revenue, data, goodwill, or business opportunity, arising out of or relating to your use of or inability to use the Service — whether based in contract, tort, negligence, strict liability, or otherwise, and even if we have been advised of the possibility of such damages.

This expressly includes any loss arising from reliance on AI output, automated grading, or content on the Service, and any academic, disciplinary, professional, or financial consequence of that reliance.

Our total aggregate liability for all claims relating to the Service will not exceed the greater of (a) the total amount you paid us in the 12 months before the event giving rise to the claim, or (b) one hundred United States dollars (USD 100).

These limitations are a fundamental basis of the bargain between us and apply even if a limited remedy fails of its essential purpose.

Some jurisdictions do not allow the exclusion or limitation of certain damages, so some of the above may not apply to you. Nothing here limits liability for death or personal injury caused by negligence, for fraud or fraudulent misrepresentation, or for any liability that cannot lawfully be limited.

18. Indemnification

You agree to indemnify, defend, and hold harmless Mathhead and its officers, directors, employees, and agents from any claim, demand, loss, liability, or expense (including reasonable legal fees) arising out of (a) Your Content, (b) your use of the Service, (c) your breach of these Terms or violation of any law or third-party right, or (d) your conduct in any class you create or run. We may assume exclusive defense of any such matter at your expense, and you agree to cooperate.

19. Dispute Resolution, Arbitration, and Class Action Waiver

PLEASE READ THIS SECTION CAREFULLY. IT AFFECTS YOUR LEGAL RIGHTS AND REQUIRES INDIVIDUAL ARBITRATION INSTEAD OF COURT PROCEEDINGS AND JURY TRIALS.

19.1 Informal resolution first. Before starting any proceeding, you agree to contact us at service@eulervertex.com with a description of the dispute and the relief you seek, and to give us 60 days to resolve it informally. We will do the same for any claim we have against you. This step is a precondition to arbitration.

19.2 Agreement to arbitrate. If we cannot resolve a dispute informally, you and Mathhead agree that any dispute, claim, or controversy arising out of or relating to these Terms or the Service will be resolved by binding individual arbitration, and not in court, except as stated in 19.4 and 19.6. Arbitration will be administered by the American Arbitration Association under its Consumer Arbitration Rules, before a single arbitrator. This agreement is governed by the Federal Arbitration Act.

19.3 Procedure. Arbitration will take place in the county where you reside, or at another mutually agreed location, or by video or telephone at your election. The arbitrator may award the same individual relief a court could, and their decision is final and binding. Where the AAA Consumer Rules apply, we will pay the filing and arbitration fees they require us to pay.

19.4 Small claims exception. Either of us may bring an individual claim in small claims court instead of arbitration, if it qualifies and stays there.

19.5 CLASS ACTION WAIVER. YOU AND MATHHEAD AGREE THAT EACH MAY BRING CLAIMS AGAINST THE OTHER ONLY IN AN INDIVIDUAL CAPACITY, AND NOT AS A PLAINTIFF OR CLASS MEMBER IN ANY CLASS, COLLECTIVE, CONSOLIDATED, OR REPRESENTATIVE PROCEEDING. The arbitrator may not consolidate claims or preside over any form of representative proceeding. If this waiver is found unenforceable as to a particular claim, that claim must proceed in court and is severed from arbitration, while all other claims remain in arbitration.

19.6 YOUR RIGHT TO OPT OUT. You may opt out of this arbitration agreement and class action waiver by emailing service@eulervertex.com with the subject line "Arbitration Opt-Out", including your name and the email address on your account, within 30 days of first accepting these Terms. Opting out affects nothing else in these Terms, and we will not treat it adversely in any way. If you opt out, disputes are resolved in court under Section 20.

19.7 Injunctive relief. Either party may seek injunctive or equitable relief in court to protect intellectual property or prevent unauthorized access to the Service.

19.8 Consumers in the EEA and UK. Nothing in this Section 19 applies to you if you are a consumer resident in the European Economic Area or the United Kingdom. You may bring proceedings in the courts of your country of residence, and you retain all rights under the mandatory consumer protection law of that country. EU consumers may also use the European Commission's Online Dispute Resolution platform.

20. Governing Law and Venue

These Terms and any dispute arising from them are governed by the laws of the State of Delaware, United States, without regard to its conflict-of-laws rules, and excluding the United Nations Convention on Contracts for the International Sale of Goods.

For any dispute not subject to arbitration, you and Mathhead consent to the exclusive jurisdiction of the state and federal courts located in Delaware, and waive any objection to venue there.

If you are a consumer, this does not deprive you of the protection of the mandatory laws of your country of residence, or of your right to bring proceedings in your local courts where the law grants you that right. California residents retain all non-waivable rights under California law.

21. Changes to These Terms

We may update these Terms. When we do, we will revise the "Last updated" date above.

If we make a material change, we will give you reasonable advance notice — by email to the address on your account or by a prominent notice in the Service — before it takes effect. Material changes do not apply retroactively, and changes to the arbitration agreement in Section 19 will not apply to a dispute of which we had notice before the change.

Continuing to use the Service after a change takes effect means you accept the updated Terms. If you do not agree, stop using the Service and cancel any subscription.

22. General

Entire agreement. These Terms, with the Privacy Policy and the Refund & Cancellation Policy, are the entire agreement between you and Mathhead about the Service, and supersede any prior agreement.

Severability. If any provision is held unenforceable, it will be limited or severed to the minimum extent necessary, and the rest remains in full force. Section 19.5 has its own severability rule.

No waiver. Our failure to enforce any provision is not a waiver of it.

Assignment. You may not assign or transfer these Terms without our written consent. We may assign them freely, including in connection with a merger, acquisition, or sale of assets.

Force majeure. Neither party is liable for any failure to perform caused by events beyond its reasonable control.

No third-party beneficiaries. These Terms create no rights in anyone other than you and Mathhead.

Notices. We may notify you by email to the address on your account or by posting in the Service. Notices to us go to service@eulervertex.com.

Headings. Headings are for convenience only and do not affect interpretation.

23. Contact Us