Terms of Use

Welcome to Stella. These Terms of Use (“Terms”) are a binding agreement between you and Northbrook PBC (“Northbrook,” “we,” “us,” or “our”), the company that operates Stella. By creating an account, connecting a phone number, or exchanging messages with Stella, you agree to these Terms. If you do not agree, do not use Stella.

1. What Stella is

Stella is a tutor you can text. Once you sign up, you can send Stella questions, screenshots, or worksheets over SMS (text messages) or through our web app at stellatutor.com, and Stella will reply with step-by-step help, explanations, and practice. Stella is powered by large language models and other artificial intelligence systems. It is a study aid, not a licensed teacher, counselor, or examiner.

2. Who can use Stella

Eligibility

You must be at least 13 years old to create a Stella account on your own. If you are under 18, a parent or legal guardian must review and agree to these Terms with you and must authorize any payment on your behalf. By using Stella, you represent that you meet these requirements.

Parents and guardians

If you are a parent or guardian creating or paying for an account for your student, you are agreeing to these Terms on behalf of yourself and your student. You are responsible for supervising your student’s use of Stella and for any charges associated with the account.

3. Accounts and phone numbers

Stella accounts are identified by a mobile phone number. You are responsible for keeping your phone, messaging app, and login credentials secure, and for all activity that happens on your account. Provide accurate information when you sign up and keep it current. If you lose access to your number, contact us so we can help you recover or close the account.

4. Messaging, carrier fees, and opt-out

By providing your phone number and signing up, you consent to receive text messages from Stella related to the service, including tutoring replies, verification codes, session reminders, and account notifications. Message frequency varies based on how often you text Stella. Message and data rates may apply from your mobile carrier. Carriers are not liable for delayed or undelivered messages.

You can reply STOP at any time to stop receiving non-essential messages, or HELP for help. Replying STOP will limit or end your ability to use Stella, because Stella works primarily over SMS.

5. Payment and subscriptions

Some features of Stella require a paid subscription. Payments are processed by our payment provider, Stripe. By starting a subscription, you authorize us (and Stripe) to charge the payment method you provide on a recurring basis until you cancel, plus any applicable taxes. Unless stated otherwise, subscription fees are non-refundable and access continues through the end of the billing period in which you cancel. You can cancel at any time from your account or by contacting us.

If a parent or guardian is paying for a student’s account, the person whose payment method is on file is the account’s payer and is responsible for all charges.

6. Acceptable use

When you use Stella, you agree not to:

• Submit another person’s phone number or personal information without their permission.
• Use Stella to cheat on a test, assessment, or assignment in a way that violates your school’s rules or academic integrity policies.
• Send content that is illegal, threatening, harassing, hateful, or sexually explicit, or that depicts or exploits minors.
• Attempt to reverse engineer, scrape, overload, or interfere with Stella, its infrastructure, or the underlying AI models.
• Resell, redistribute, or build a competing product using Stella’s outputs.
• Use Stella in a way that violates any applicable law or regulation.

We may suspend or close accounts that violate these rules or that cause harm to other users or the service.

7. AI outputs and academic honesty

Stella generates responses using AI, which means it can be wrong, incomplete, or outdated. Always double-check important answers — for example, with a textbook, a teacher, or an official source — before relying on them. Stella is designed to help you learn, not to take tests for you. You are responsible for following your school’s rules about acceptable help on homework, assessments, and college applications.

Stella is not a substitute for professional advice. It does not provide medical, mental-health, legal, or financial advice. If you are in crisis or need urgent help, contact a qualified professional or local emergency services.

8. Your content

You keep ownership of the messages, images, and documents you send to Stella (“your content”). By sending your content to Stella, you grant Northbrook a worldwide, non-exclusive, royalty-free license to store, process, display, and use your content as needed to operate, improve, and secure the service, and to comply with the law. We describe how we handle your content in more detail in our Privacy Policy.

Don’t send Stella anything you don’t have the right to share, or anything you wouldn’t want us to see in order to deliver the service.

9. Our content and intellectual property

Stella, the Stella name and logo, the web app, and all software, text, graphics, and designs we provide are owned by Northbrook or our licensors and are protected by intellectual-property laws. We grant you a limited, non-exclusive, non-transferable, revocable license to access and use Stella for your personal, non-commercial learning. All rights not expressly granted are reserved.

You may use Stella’s outputs for your own learning, schoolwork, and personal projects, subject to these Terms and to your school’s rules. You remain responsible for how you use those outputs.

10. Third-party services

Stella relies on third parties to function, including messaging carriers, hosting providers, and AI model providers. Their systems are governed by their own terms, and we are not responsible for outages, bugs, or decisions those providers make. Links from Stella to third-party sites are provided for convenience only.

11. Termination

You can stop using Stella at any time, and you can ask us to close your account by contacting us. We may suspend or terminate your access at any time if you violate these Terms, if we’re required to by law, or if continuing to provide the service would expose us or other users to risk. Sections of these Terms that by their nature should survive termination — including sections 8, 9, 12, 13, 14, and 15 — will survive.

12. Disclaimers

Stella is provided “as is” and “as available.” To the fullest extent permitted by law, Northbrook disclaims all warranties, express or implied, including warranties of merchantability, fitness for a particular purpose, non-infringement, and any warranty that Stella will be uninterrupted, accurate, timely, secure, or error-free. You use Stella at your own risk.

13. Limitation of liability

To the fullest extent permitted by law, Northbrook and its officers, directors, employees, and agents will not be liable for any indirect, incidental, special, consequential, exemplary, or punitive damages, or any loss of profits, revenue, data, or goodwill, arising out of or related to your use of Stella — even if we’ve been advised of the possibility of those damages. Our total liability for any claim related to Stella will not exceed the greater of (a) the amount you paid us in the 12 months before the claim arose, or (b) USD $100.

Some jurisdictions do not allow certain limitations, so some of the above may not apply to you.

14. Indemnification

You agree to defend, indemnify, and hold harmless Northbrook and its personnel from any claims, damages, liabilities, and expenses (including reasonable attorneys’ fees) that arise out of your content, your use of Stella, or your violation of these Terms.

15. Governing law and disputes

These Terms are governed by the laws of the State of Delaware, without regard to conflict-of-laws rules. Any dispute arising out of or relating to these Terms or Stella will be resolved exclusively in the state or federal courts located in Delaware, and you and Northbrook consent to personal jurisdiction there. If you are a consumer residing in a jurisdiction whose law gives you the right to bring a claim in local courts, nothing in this section removes that right.

16. Changes to these Terms

We may update these Terms from time to time. When we make material changes, we’ll update the “Last updated” date above and, when appropriate, notify you by text message or through the app. Your continued use of Stella after changes take effect means you accept the updated Terms.

17. Contact

Questions about these Terms? Email us at team@northbrook.com.

Northbrook PBC
Operator of Stella