These Terms of Service govern your use of the Vitnis cloud service. They are a legally binding agreement between you and Vitnis Ltd, Reg.Office: 71-75 Shelton Street, Covent Garden, London, WC2H 9JQ Reg. in England No. 17201606. By creating an account, subscribing to a paid tier, or using the Vitnis service, you accept these Terms.
These Terms apply to self-serve tiers (Free Account, Academic, Starter, Pro, and Business). Enterprise customers are governed by their bilateral contract with Vitnis, which supersedes these Terms in the event of any conflict.
If you do not accept these Terms, do not use the Vitnis service.
In these Terms:
By creating an account, accessing the Service, or accepting these Terms during signup, you represent that:
You may not use the Service if:
By using the Service, you warrant that none of these conditions apply.
The Academic tier is available only to verified academic institutions and registered non-profits. Vitnis reserves the right to verify eligibility and to terminate access where eligibility cannot be confirmed.
Vitnis provides classical numerical verification of quantum circuit specifications. The Service computes the measurements for a submitted Circuit and returns a cryptographically signed Receipt attesting the result.
The Service is validated to produce 100%-accurate results within a defined operating envelope (depth ≤ 4). Results outside this envelope are returned with a SILVER or WARNING certification flag, including quantified accuracy bounds where applicable. Customers are responsible for understanding the certification level of any result they rely upon.
Receipts are signed using ECDSA over the NIST P-256 curve (SECP256R1) with SHA-256, as standardised by FIPS 186-5. The corresponding public key is published at /.well-known/signing-key.pem for offline verification.
The Service is provided on an “as available” basis. Vitnis does not guarantee uptime or service availability for self-serve tiers. While we will use reasonable efforts to maintain Service availability, we make no commitment to specific uptime levels for self-serve tiers.
We may modify, update, or discontinue features of the Service from time to time. Material changes affecting your tier will be notified by email at least 30 days in advance, in accordance with our pricing update policy.
You must create an account to access tiers above the anonymous demo. Authentication is provided by Clerk (https://clerk.com), a third-party identity provider, in accordance with our Privacy Policy.
You are responsible for:
We are not liable for any loss arising from your failure to maintain the security of your account.
You may not create multiple accounts to circumvent tier limits or restrictions. Where multiple accounts are detected and appear to share a single user, Vitnis may consolidate or terminate them at our discretion.
Subscriptions to Starter, Pro, and Business tiers are billed monthly in advance. Pricing is as published on our pricing page at the time of subscription, subject to the price lock described below.
Payment is processed by Stripe (https://stripe.com). By subscribing, you accept Stripe's terms of service and privacy policy in addition to ours. Vitnis does not receive or store your payment card details.
Subscriptions automatically renew at the end of each billing cycle unless cancelled. By subscribing, you authorise Vitnis (via Stripe) to charge your payment method for each renewal until you cancel.
You may cancel your Subscription at any time through your account dashboard or by contacting us. On cancellation:
If you are subscribing as a consumer (not in the course of a business) and this is your first Subscription with Vitnis, you have the right to cancel within 14 days of your first subscription date and receive a full refund. This cooling-off right does not apply to:
To exercise this right, email hello@vitnis.com within 14 days of your first subscription date.
Subscriptions to self-serve paid tiers (Starter, Pro, Business) are subject to a 24-month price lock from the date of original subscription. During this period, the price you pay will not change. After 24 months, prices may be updated subject to the change-management policy on our pricing page.
If a payment fails, we may:
Prices are exclusive of applicable taxes (VAT, sales tax, GST, etc.). Tax is calculated and applied by Stripe based on your billing location and is your responsibility.
Free Account and Academic tiers are provided at no charge. Vitnis reserves the right to modify the terms, limits, or availability of free tiers with 30 days' notice.
Each tier includes a monthly Credit allocation as described on the pricing page. Credits are consumed by verification requests at rates that depend on circuit size and complexity.
Credits refresh monthly on your subscription anniversary date. Unused Credits do not roll over to subsequent months.
When your Credit wallet is exhausted, verification requests will be rejected until the next refresh date or until you upgrade to a higher tier.
Daily rate limits apply to all tiers as published on our pricing page. Rate limits are intended to prevent burst-rate abuse and ensure fair resource allocation. Tier-appropriate rate limits are calibrated to support typical usage patterns.
The exact formula for Credit consumption per verification is internal to Vitnis. Approximate examples are provided on the pricing page. Vitnis may adjust the formula from time to time within the bounds of reasonable economic correspondence to compute cost; material adjustments affecting your tier will be notified in advance.
You may use the Service for any lawful purpose consistent with these Terms, including for commercial use of verification results within your own products and services, subject to the restrictions below.
You must not:
You acknowledge that the Service is subject to UK export control regulations. By using the Service, you warrant that your use complies with all applicable export controls, sanctions, and end-use restrictions.
You retain all rights, title, and interest in the quantum circuits you submit to the Service. We do not claim ownership of your Circuits. We process your Circuits in volatile memory only and do not retain them beyond the duration of the verification request.
You own the Receipts produced for your Circuits. You may use, share, publish, or distribute Receipts freely, including in commercial products and academic publications. Vitnis retains:
The Service, including the verification engine, software, documentation, branding, and all related materials, is the intellectual property of Vitnis. We grant you a limited, non-exclusive, non-transferable, revocable licence to use the Service in accordance with these Terms.
You may not:
The numerical methodology underlying the Service (matrix-product-state tensor-network simulation) is established public-domain numerical analysis. These Terms do not restrict your use of the underlying public-domain methodology; only of the proprietary Vitnis implementation.
Vitnis commits to publishing the public verification keys for all signed Receipts at /.well-known/signing-key.pem (or successor URL with reasonable notice).
In the event that Vitnis ceases active operation, we commit to maintaining public key publication for at least 7 years from the date of any Receipt issued. This commitment is intended to ensure that Receipts remain independently verifiable for the duration of their commercial usefulness.
Where signing keys are rotated for security reasons, we will publish both old and new public keys for an overlap period and clearly mark which keys signed which Receipts.
Our handling of personal data is governed by our Privacy Policy, which is incorporated into these Terms by reference. Key points:
For full details, see our Privacy Policy.
The Service is provided on an “as is” and “as available” basis. To the fullest extent permitted by law, Vitnis disclaims all warranties, express or implied, including warranties of merchantability, fitness for a particular purpose, and non-infringement, except as expressly stated in these Terms.
Vitnis Verifier provides verification of quantum circuit specifications. Customers are responsible for their own decisions made using verification results. Vitnis's liability for any error in verification is limited as described in this Section and does not extend to consequential losses incurred by the Customer or any third party as a result of decisions made on the basis of verification results.
The Service produces results within a defined operating envelope, with certification levels (GOLD, SILVER, WARNING) reflecting the confidence appropriate to each result. Customers are responsible for understanding the certification level of results they rely upon.
To the fullest extent permitted by law, Vitnis's total aggregate liability arising from or relating to these Terms or the Service is limited to the lesser of:
This limitation applies whether the claim is brought in contract, tort (including negligence), strict liability, statute, or any other theory.
The limitations in Section 11.3 do not apply to:
To the fullest extent permitted by law, Vitnis is not liable for any indirect, incidental, special, consequential, or punitive damages, including but not limited to lost profits, lost data, business interruption, or loss of business opportunity.
You acknowledge that:
You agree to indemnify and hold harmless Vitnis, its successors, and assigns from any claims, damages, losses, liabilities, costs, and expenses (including reasonable legal fees) arising from:
You may terminate your account at any time by:
On termination:
We may terminate or suspend your account, with or without notice, for:
On termination by Vitnis:
Neither party is liable for failure to perform obligations under these Terms to the extent that performance is prevented by circumstances beyond reasonable control, including but not limited to: natural disasters, war, terrorism, pandemics, government actions, internet or infrastructure outages, supply chain disruptions, or labour disputes. The affected party will notify the other promptly and resume performance as soon as practicable.
This section does not apply to payment obligations.
We will give notices to you by email to the address registered with your account. It is your responsibility to keep your email address current. Notices are deemed received on the day of sending unless we receive notice of delivery failure.
You may give notice to us by email to:
Notices are deemed received on the next business day after sending.
We will notify you by email of material changes to these Terms at least 30 days before they take effect. Continued use of the Service after the effective date constitutes acceptance of the updated Terms.
Before commencing any formal legal action, the parties agree to attempt to resolve any dispute through informal negotiation. The party raising the dispute will:
This requirement does not apply to claims for injunctive or equitable relief, where time is of the essence.
These Terms are governed by and construed in accordance with the laws of England and Wales.
The courts of England and Wales have exclusive jurisdiction over any dispute arising from or relating to these Terms or the Service, except that we may bring an action in any court of competent jurisdiction to seek injunctive or equitable relief, or to enforce a judgment.
These Terms, together with our Privacy Policy and any other documents incorporated by reference, constitute the entire agreement between you and Vitnis regarding the Service. They supersede any prior agreements, understandings, or representations.
We may modify these Terms from time to time. Material changes will be notified by email at least 30 days before they take effect. Your continued use of the Service after the effective date constitutes acceptance of the modified Terms. If you do not accept the modifications, you must stop using the Service.
If any provision of these Terms is held to be invalid, illegal, or unenforceable, the remaining provisions remain in full effect. The invalid provision will be modified to the minimum extent necessary to make it valid, while preserving the parties' original intent.
Our failure to enforce any provision of these Terms does not constitute a waiver of that provision or any other.
You may not assign or transfer your rights or obligations under these Terms without our prior written consent. We may assign these Terms without your consent in connection with a merger, acquisition, sale of substantially all of our assets, or by operation of law.
These Terms do not create any partnership, joint venture, agency, or employment relationship between you and Vitnis. Neither party has authority to bind the other.
These Terms do not confer any rights on any third party. The Contracts (Rights of Third Parties) Act 1999 does not apply.
Headings are for convenience only and do not affect the interpretation of these Terms.
For questions about these Terms:
| Version | Date | Notes |
|---|---|---|
| 1.0 | 2026-05-28 | Initial Terms of Service. Effective from launch of cloud service. |
These Terms of Service are governed by the laws of England and Wales.