Terms of Service

Effective 2026-05-23. These Terms of Service (the "Terms") are a binding contract between you ("you", "User") and Plinth ("we", "us", "Plinth"). By creating an account, completing a purchase, or otherwise using Plinth — including the website at plinthprep.com, any subdomain, the API if and when published, and any future Plinth client application (collectively, the "Service") — you agree to these Terms in full. If you do not agree, do not use the Service.

1. The Service

Plinth provides a study tool for the Claude Certified Architect — Foundations (CCA-F) exam. The Service consists of a curated question pool, mock examination, weak-spot drill, flashcards, a Compendium, and other study aids. The Service is sold as a one-time purchase granting lifetime access to the features available to that tier on the date of purchase. "Lifetime" means for as long as the Service continues to operate; we make no commitment as to how long that will be (see Sections 12 and 13).

We may add, remove, or change features. We may modify or discontinue functionality, content, or third-party integrations without notice. We will not knowingly remove a core feature that you paid to access without offering a substitute or, at our discretion, a partial refund proportionate to the time elapsed since purchase.

2. Eligibility

You may use the Service only if you can form a binding contract with Plinth. By using the Service, you represent that:

• You are at least 16 years old. The Service is not directed at, and is not designed for, children under 16. If you are between 16 and the age of majority in your jurisdiction, you confirm that your parent or legal guardian has reviewed and consented to these Terms.
• You have the legal capacity and authority to agree to these Terms.
• You are not on any U.S. or other applicable sanctions list, and you are not located in a country subject to a U.S. government embargo.
• You have not previously been suspended or removed from the Service.

We may, at our discretion, decline service to anyone for any non-discriminatory reason.

3. Accounts

You may use a limited subset of the Service anonymously. Beyond that subset, you must create an account using a working email address. You are responsible for:

• Providing accurate, complete, and current registration information.
• Maintaining the confidentiality of any password or authentication credential.
• Restricting access to your account; you accept responsibility for all activities that occur under it.
• Notifying us promptly at support@plinthprep.com if you suspect unauthorized use of your account.

Plinth is licensed to a single individual user. You may not share account credentials with anyone else. Each paid purchase grants access to one user only.

4. Payment, taxes, and billing

4.1 Pricing. The price of the Service, the currency, and any applicable taxes are shown at checkout. Prices may change for future purchasers; price changes do not affect a previously completed purchase.

4.2 Payment processor. Payments are processed by Stripe, Inc. under Stripe's Services Agreement and Privacy Policy. We never see your full card number; Stripe holds the cardholder data.

4.3 Authorization. By submitting payment information, you authorize Plinth (via Stripe) to charge the payment method for the amount shown, plus any applicable taxes. You represent that you are the authorized user of the payment method.

4.4 Sales tax. Plinth collects sales tax in jurisdictions where it holds an active tax registration. Tax is added to your purchase price at checkout based on your billing address. You are responsible for any use tax, VAT, or similar tax owed in jurisdictions where Plinth does not collect.

4.5 Receipts. Stripe issues an email receipt for each purchase. You can also retrieve receipts from your account settings.

4.6 Chargebacks. If you dispute a charge with your bank or card network instead of contacting support@plinthprep.com first, we reserve the right to immediately suspend your account, revoke access, and contest the chargeback with evidence of authorized purchase and Service delivery. Filing a fraudulent chargeback constitutes a material breach of these Terms and may result in legal action to recover the charged amount plus reasonable fees.

5. Refunds

All sales of Plinth Pro are final. In exchange, your purchase grants lifetime access — including every future question, feature, and Stem Decoder update we ship. The free preview is available before purchase so you can evaluate the product. Narrow exceptions (duplicate billing, entitlement failure, mandatory consumer-protection law, service discontinuation) are set out in the Refund Policy, which is incorporated into these Terms by reference.

6. License grant

Subject to your compliance with these Terms, Plinth grants you a limited, non-exclusive, non-transferable, non-sublicensable, revocable license to access and use the Service for your personal, non-commercial exam preparation. The license is granted to a single individual and is tied to your account. The license does not transfer with any sale of any device, account credentials, or other asset.

7. Acceptable use

You agree NOT to:

• Resell, redistribute, republish, sublicense, or display any Plinth content (including question stems, answer choices, explanations, the Compendium, the Stem Decoder, flashcards, or any portion of the mock exam) in any form, paid or free, public or private.
• Scrape, crawl, harvest, or systematically extract Service content, with or without automated means, except via any official API we publish under terms that allow it.
• Use the Service or its content to train, fine-tune, evaluate, or benchmark any machine-learning model, including any large language model, transformer, retrieval system, or derivative.
• Reverse engineer, decompile, or attempt to extract the source code of the Service except to the extent expressly permitted by applicable law.
• Share, sell, gift, lend, or transfer your account credentials or lifetime-access entitlement to any other person.
• Use the Service to cheat on, leak, or compromise the actual Claude Certified Architect exam, including but not limited to attempting to memorize and reproduce real exam questions through the Service.
• Access the Service via any means other than the interfaces we provide (web app, official mobile clients if and when released, any official API).
• Attempt to gain unauthorized access to any portion of the Service, any other user's account, or any of our or our vendors' systems.
• Interfere with, disrupt, or attempt to denial-of-service the Service, our hosting providers, or other users.
• Submit, upload, or transmit any material that contains malware, viruses, trojans, or other code designed to harm any system or interfere with its functioning.
• Use the Service in violation of any law, regulation, or court order, or to harass, defame, threaten, or violate the rights of any person.
• Misrepresent your identity, impersonate any person, or falsely claim affiliation with Plinth, Anthropic, or any other entity.
• Bypass, attempt to bypass, or describe how to bypass any access control, paywall, rate limit, or technical protection on the Service.

We monitor for and may automatically detect violations. Violations may result in immediate suspension or termination of access with no refund, and may give rise to civil or criminal claims.

8. Intellectual property

8.1 Plinth's IP. All Plinth-original content — including the question pool, explanations, the Compendium, the Stem Decoder, the mock exam configuration, the user interface, source code, branding (the Plinth mark, the "Plinth Prep" wordmark, the "Foundations, drilled." tagline), and any related documentation — is the sole property of Plinth and its licensors, protected by copyright, trademark, trade dress, and other applicable laws. All rights not expressly granted to you in these Terms are reserved.

8.2 Anthropic content. The Service references the Claude Certified Architect exam, Anthropic's published documentation, and the Claude trademark for educational and descriptive purposes. Anthropic and "Claude" are trademarks of Anthropic, PBC. We claim no affiliation with, sponsorship by, or endorsement from Anthropic.

8.3 User feedback. If you send us suggestions, corrections, or ideas (collectively, "Feedback"), you grant Plinth a worldwide, perpetual, irrevocable, royalty-free, sublicensable, transferable license to use, reproduce, modify, and incorporate the Feedback into the Service without compensation or attribution. We are not obligated to act on Feedback.

8.4 User content. The Service does not currently solicit or display user-generated content publicly. To the extent you submit any text, file, or material to Plinth (e.g., a question correction with your own explanation), you grant Plinth a non-exclusive, royalty-free license to use that submission to operate, improve, and provide the Service.

9. DMCA and copyright complaints

If you believe content on the Service infringes your copyright, send a written notice to admin@plinthprep.com that includes:

1. A physical or electronic signature of the copyright owner or an authorized agent.
2. Identification of the copyrighted work claimed to have been infringed.
3. Identification of the material claimed to be infringing, sufficient for us to locate it (e.g., a question ID, URL, or section identifier).
4. Your name, address, telephone number, and email.
5. A statement that you have a good-faith belief that the use is not authorized.
6. A statement, under penalty of perjury, that the information is accurate and you are authorized to act on the copyright owner's behalf.

We will respond consistent with the U.S. Digital Millennium Copyright Act (17 U.S.C. § 512). We will, in appropriate circumstances, terminate the accounts of repeat infringers.

10. Trademarks

"Plinth", "Plinth Prep", the Plinth mark, the "~/plinth $" wordmark, and the "Foundations, drilled." tagline are trademarks of Plinth. You may not use them without prior written permission, except in factual references (e.g., "I used Plinth to study for the CCA-F exam"). All other trademarks are the property of their respective owners.

11. Third-party services

The Service relies on third-party providers, each subject to their own terms and privacy practices:

Vendor	Role	Their terms
Stripe, Inc.	Payment processing	stripe.com/legal
Supabase, Inc.	Database & authentication	supabase.com/terms
Vercel, Inc.	Hosting & CDN	vercel.com/legal/terms
Resend, Inc.	Transactional email	resend.com/legal

We are not responsible for any third party's act, omission, error, downtime, security incident, or change to its terms. We may add, remove, or substitute vendors without notice.

12. Termination and suspension

12.1 By you. You may stop using the Service at any time. You may request account deletion from support@plinthprep.com; we will delete your account within 30 days of the request, subject to legal retention requirements.

12.2 By us. We may suspend or terminate your access, in whole or in part, without notice, if we reasonably believe you have:

• Violated Section 7 (Acceptable use), Section 8 (IP), or any other material provision of these Terms.
• Filed a chargeback or refund-fraud claim in bad faith.
• Created a security or legal risk for Plinth, our vendors, or other users.
• Used the Service to violate the law.

Termination for cause forfeits all access and any unused entitlement, without refund.

12.3 Service discontinuation. We may discontinue the Service entirely. If we do, we will provide reasonable notice via email and will, at our discretion, offer a pro-rated refund to active paid users based on the time elapsed since purchase, up to but not exceeding the original purchase amount.

12.4 Survival. Sections 4 (Payment, taxes, billing), 5 (Refunds), 7 (Acceptable use), 8 (IP), 13 (Disclaimers), 14 (Limitation of liability), 15 (Indemnification), 17 (Dispute resolution), 18 (Governing law), and 20 (Miscellaneous) survive termination.

13. Disclaimers

THE SERVICE IS PROVIDED "AS IS" AND "AS AVAILABLE", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. To the maximum extent permitted by law, Plinth disclaims all warranties, including but not limited to warranties of merchantability, fitness for a particular purpose, non-infringement, accuracy, completeness, reliability, security, uptime, and quiet enjoyment.

Without limiting the foregoing, Plinth specifically does NOT warrant or guarantee:

• That you will pass the Claude Certified Architect exam, or any other exam, by using the Service.
• That the Service is or will be error-free, uninterrupted, secure, or free of viruses or other harmful components.
• That all explanations, question rationales, or study aids are accurate; we make a good-faith effort, but errors occur and corrections are issued via the Service.
• That the Service's content reflects the most current version of the actual exam blueprint at any given moment.
• That any third-party service or content linked from the Service remains available, accurate, or appropriate.

You assume sole responsibility for any decision you make based on the Service. The Service is not legal, financial, tax, medical, or career advice.

14. Limitation of liability

TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW:

• IN NO EVENT WILL PLINTH, ITS FOUNDER, OFFICERS, EMPLOYEES, CONTRACTORS, OR VENDORS BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, EXEMPLARY, OR PUNITIVE DAMAGES, OR FOR ANY LOSS OF PROFITS, REVENUE, DATA, USE, GOODWILL, OR OTHER INTANGIBLE LOSSES, ARISING OUT OF OR RELATED TO YOUR USE OF, OR INABILITY TO USE, THE SERVICE — EVEN IF PLINTH HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
• PLINTH'S TOTAL CUMULATIVE LIABILITY TO YOU FOR ALL CLAIMS, IN AGGREGATE, WILL NOT EXCEED THE GREATER OF (A) THE AMOUNT YOU PAID PLINTH IN THE 12 MONTHS PRECEDING THE EVENT GIVING RISE TO THE CLAIM, OR (B) US$50.

Some jurisdictions do not allow the exclusion or limitation of certain damages. In those jurisdictions, the foregoing limitations apply to the maximum extent permitted by law. Nothing in these Terms limits liability for fraud or willful misconduct, or any liability that cannot be excluded by law.

15. Indemnification

You agree to indemnify, defend, and hold harmless Plinth, its founder, employees, contractors, and vendors from and against any and all claims, demands, losses, liabilities, damages, costs, and expenses (including reasonable attorneys' fees) arising out of or related to:

• Your use of the Service in violation of these Terms;
• Your violation of any applicable law;
• Your infringement of any intellectual property right or other right of any third party;
• Any content or information you submit to the Service.

We reserve the right, at your expense, to assume the exclusive defense and control of any matter subject to indemnification by you; you agree to cooperate with our defense.

16. Force majeure

Plinth is not liable for any failure or delay in performance caused by events beyond its reasonable control, including but not limited to: acts of God, natural disasters, war, terrorism, civil disturbance, pandemic, government action, internet outages, third-party service-provider outages, cyber attacks, or labor disputes.

17. Dispute resolution

17.1 Informal resolution. Before filing any claim, you agree to contact admin@plinthprep.com with a description of the dispute and a proposed resolution. We will attempt in good faith to resolve the dispute by email within 30 days.

17.2 Binding arbitration. If informal resolution fails, any dispute, claim, or controversy arising out of or relating to these Terms or the Service will be resolved by binding individual arbitration administered by JAMS under its Streamlined Arbitration Rules, in King County, Washington, in English, before a single arbitrator. Judgment on the award may be entered in any court of competent jurisdiction.

17.3 Class action waiver. You agree to resolve disputes with Plinth on an individual basis only. You waive the right to participate in a class action, class arbitration, or any consolidated proceeding. The arbitrator may not consolidate more than one person's claims and may not preside over any form of representative proceeding.

17.4 Opt-out. You may opt out of Sections 17.2 and 17.3 by emailing admin@plinthprep.com within 30 days of first accepting these Terms, with the subject line "Arbitration opt-out" and your name and account email in the body. If you opt out, the rest of these Terms still apply.

17.5 Carve-outs. Notwithstanding the foregoing, either party may bring an individual action in small-claims court, or seek injunctive or equitable relief in any court of competent jurisdiction to protect intellectual property or confidential information.

18. Governing law

These Terms are governed by the laws of the State of Washington, United States, without regard to its conflict-of-laws principles. The United Nations Convention on Contracts for the International Sale of Goods does not apply. Subject to Section 17 (Dispute resolution), the state and federal courts located in King County, Washington have exclusive jurisdiction over any non-arbitrable matter.

19. Changes to these Terms

We may amend these Terms at any time by posting a revised version at plinthprep.com/terms with a new "Effective" date. For material changes, we will provide reasonable advance notice (at least 14 days) via in-product notification or email to the address on file. Continued use of the Service after the effective date of a revision constitutes acceptance of the revised Terms. If you do not agree to a revision, you must stop using the Service and may request a refund under the Refund Policy if applicable.

20. Miscellaneous

20.1 Entire agreement. These Terms, together with the Privacy Policy and Refund Policy, constitute the entire agreement between you and Plinth and supersede all prior or contemporaneous understandings.

20.2 Severability. If any provision is held unenforceable, the remaining provisions remain in full force and effect, and the unenforceable provision will be modified to the minimum extent necessary to be enforceable while preserving its intent.

20.3 No waiver. Our failure to enforce any provision is not a waiver of our right to do so later.

20.4 Assignment. You may not assign or transfer these Terms or any rights or obligations hereunder without our prior written consent. Plinth may assign these Terms freely, including to a successor in a merger, acquisition, or sale of assets.

20.5 Independent contractors. Nothing in these Terms creates an agency, partnership, joint venture, employment, or franchise relationship.

20.6 Headings. Section headings are for convenience only and do not affect interpretation.

20.7 Notices. Notices to you may be sent to the email associated with your account. Notices to Plinth must be sent to admin@plinthprep.com. Notices are effective when sent.

20.8 Export control. You agree to comply with U.S. export-control laws and other applicable export and import laws, and you confirm you are not located in a country subject to a U.S. government embargo.

20.9 Government users. The Service is "commercial computer software" and "commercial computer software documentation". U.S. government users acquire only those rights set forth herein.

20.10 Electronic communications. You consent to receive electronic communications from us, including those required by law. Electronic communications satisfy any legal requirement that such communications be in writing.

21. Contact

Questions about these Terms: admin@plinthprep.com.

Operator: John Ryu, doing business as Plinth, Washington, United States.