Terms of Service

Last updated: 30 July 2026

These Terms of Service (“Terms”) constitute a binding agreement between you and ZKSF (“we”, “us” or “our”) governing your access to and use of the ZKSF platform, application programming interface and related services (the “Service”). Please read Sections 9 to 14 carefully: they allocate risk to you, limit our liability and require you to indemnify us in defined circumstances.

1. Acceptance of Terms

• By creating an account, submitting a job or otherwise accessing the Service, you accept these Terms in full. If you do not accept them, you must not use the Service.
• Where you use the Service on behalf of an organisation, you warrant that you have authority to bind that organisation, and references to “you” include it.
• You must have the legal capacity to enter into a binding contract, and must not use the Service where doing so would be unlawful in your jurisdiction.

2. The Service

• ZKSF provides cloud based classical simulation of quantum circuits on high performance compute, together with access to real quantum processing units on third party quantum hardware, through a single service and API.
• Simulation methods include exact statevector, stabilizer and approximate tensor network techniques. Approximate methods carry method dependent accuracy limits, which are reported with each result.
• The Service may decline to execute a circuit it cannot run reliably. Rejection diagnostics are provided on a best efforts basis and rejections are not charged.
• We may modify, suspend or discontinue features at any time, and will give reasonable notice of material reductions in functionality where practicable.

3. Experimental Technology

You expressly acknowledge that quantum computing and quantum simulation are emerging and experimental fields. Methods, error models, calibration and hardware behaviour are the subject of active research and may produce results that are unexpected, unstable, irreproducible or unsuitable for a given purpose, without any indication that this has occurred. These are inherent characteristics of the field and are not defects in the Service.

4. Accuracy and Reliance

• Exact simulations are exact only up to floating point precision and sampling noise.
• Approximate simulations return estimates. Accompanying error indicators, such as convergence deviation, are evidence based estimates and not mathematical guarantees, unless expressly labelled as certified bounds.
• Results obtained from third party quantum hardware reflect that hardware’s physical noise and calibration. We neither control nor warrant hardware fidelity.
• You are responsible for validating every result before relying on it in research, publication, engineering or commercial decision making.
• You are solely responsible for any decision, publication, product, experiment or commercial action taken in reliance on a result or certificate, and we accept no responsibility for any outcome, loss or consequence arising from that reliance.

5. Certification Protocols

• ZCC-v0.1, the ZKSF Convergence Certificate for simulated results, and ZHF-v0.1, the ZKSF Hardware Fidelity certificate for hardware results, are in house protocols developed, versioned and maintained by us.
• The specification and methodology of both protocols are published openly. Citing them, independently reproducing them, or referencing certificate methodology in your own work is expressly permitted.
• A certificate records the method, parameters and accuracy or fidelity statement applicable to the specific job from which it was generated. It is not a warranty of correctness beyond what that statement itself asserts, and it does not constitute validation of your research.
• You must not present a certificate as an endorsement, accreditation or guarantee by us of any result, product or claim.

6. Data You Submit

Circuits, parameters and account information are collected and stored because you have instructed us to execute them and because the Service cannot run, price or return a job otherwise. Submission is inherent to using the Service, and it is not possible to use the Service while withholding that authorisation. We do not sell or share your information, save for transmitting a circuit to a hardware provider you have expressly selected. You warrant that you are entitled to submit everything you submit and that doing so does not infringe the rights of any third party.

7. Accounts, Tokens and Acceptable Use

• You are responsible for safeguarding your API tokens. All activity carried out under your token is attributed to your account and is your responsibility.
• You must not attempt to breach, overload, disrupt or circumvent the Service or its usage limits, use it to process unlawful content, resell access without written agreement, or attempt to access another user’s data, circuits or results.
• Reverse engineering of the Service is prohibited except to the extent that such a restriction is void by law. Benchmarking the Service and publishing the results is expressly permitted and encouraged.
• We may investigate suspected breaches and may suspend access where necessary to protect the Service, its users or any third party.

8. Fees and Billing

• Usage is billed per job by reference to compute time and resources consumed, at the rates published on the pricing page, with a pre run estimate available for every job.
• Pre run estimates are good faith predictions and not quotations. Actual billed time may differ. Estimates are deliberately conservative.
• Hardware charges are passed through at provider cost. Provider price changes take effect when the provider applies them.
• Payments are processed by an external provider certified to PCI DSS. Card data is handled entirely by that provider and never reaches our systems.
• Disputed charges must be raised within thirty days of the relevant invoice.
• Fees are exclusive of taxes, for which you are responsible.

9. Refunds

• Charges are final and non refundable. Every job consumes real compute, and for hardware jobs incurs a real third party charge, at the moment it executes, so the cost is incurred whether or not the result is the one you hoped for.
• In exchange we keep pricing deliberately low so that laboratories, students and independent researchers can afford the Service, and every job displays a conservative cost estimate before you commit to running it.
• Where you were billed for a job that failed because of a fault in the Service itself, as distinct from a rejected circuit or user error, contact us within thirty days and we will credit it.
• This does not affect any statutory right that cannot be excluded by law.

10. Intellectual Property

• You retain all rights in the circuits you submit and the results you receive. We claim no ownership of your science and assert no publication or authorship rights over it.
• We retain job metadata, being sizes, timings, methods and resource use, in order to operate, debug and improve routing and estimation. Circuit contents are not used to train models made available to others and are not shared with third parties, save as required to execute a job on hardware you have selected.
• The Service itself, including its software, interfaces, protocols and marks, is owned by us and protected by intellectual property law. Nothing in these Terms transfers ownership of it to you.

11. Availability

• The Service is provided without any uptime guarantee unless covered by a separate written service level agreement.
• Cold start latency, queue times and third party hardware availability windows vary and are not warranted.
• We do not warrant that the Service will be uninterrupted, timely, secure or error free, or that defects will be corrected.

12. Disclaimer of Warranties

To the maximum extent permitted by applicable law, the Service is provided on an “as is” and “as available” basis, without warranty, condition or representation of any kind, whether express, implied or statutory, including any implied warranty of merchantability, satisfactory quality, fitness for a particular purpose, accuracy or non infringement. Nothing in this Section excludes any warranty that cannot lawfully be excluded.

13. Limitation of Liability

• To the maximum extent permitted by law, we shall not be liable for any indirect, incidental, special, consequential, exemplary or punitive damages, nor for any loss of profit, revenue, business, opportunity, goodwill, data, research time or research outcome, however caused and under any theory of liability.
• To the maximum extent permitted by law, our aggregate liability arising out of or in connection with the Service and these Terms shall not exceed the total amount paid by you to us in the three months immediately preceding the event giving rise to the claim.
• These limitations apply regardless of the legal theory on which a claim is brought, survive termination, and reflect a reasonable allocation of risk that forms an essential basis of the agreement between us.
• Nothing in these Terms excludes liability for death or personal injury caused by negligence, for fraud, or for any other liability that cannot lawfully be excluded.

14. Indemnification

You agree to indemnify, defend and hold harmless ZKSF and its owners, officers, employees and contractors from and against any claims, demands, proceedings, liabilities, damages, losses, penalties, costs and expenses, including reasonable legal fees, arising out of or relating to: the circuits, data or content you submit; your use of, publication of, or reliance on any result or certificate; your breach of these Terms or of any applicable law; your infringement of the rights of any third party; and any claim connected with your research, product or commercial activity. We may, at our own expense, assume exclusive defence and control of any matter subject to indemnification by you, in which case you agree to cooperate. This indemnity survives termination.

15. Export Control and Sanctions

• You agree to comply with all applicable export control and sanctions laws, including restrictions on access from embargoed jurisdictions, and you warrant that you are not subject to any such restriction.
• Quantum hardware access may be subject to further provider level restrictions beyond our control.

16. Suspension and Termination

• You may close your account at any time. Closure does not entitle you to a refund of charges already incurred.
• We may suspend or terminate an account for breach of these Terms, for non payment, or for activity that endangers the Service or other users, with notice where practicable.
• Provisions concerning intellectual property, disclaimers, limitation of liability, indemnification and governing law survive termination.

17. Changes to These Terms

We may amend these Terms from time to time. The date at the head of this page records the current version. Material changes are notified by email to the address held on your account before taking effect. Continued use of the Service after that date constitutes acceptance. If you do not accept an amendment, you must stop using the Service.

18. General Provisions

• Entire agreement. These Terms and the Privacy Policy constitute the entire agreement between the parties concerning the Service.
• Severability. If any provision is held invalid or unenforceable it shall be modified to the minimum extent necessary, or severed, and the remainder continues in force.
• No waiver. Failure or delay in enforcing a provision is not a waiver of it.
• Assignment. You may not assign these Terms without our written consent. We may assign them in connection with a merger, acquisition or sale of assets.
• Force majeure. We are not liable for failure or delay caused by events beyond our reasonable control.
• Claims period. Any claim must be brought within one year after the cause of action arises, or within such longer period as applicable law requires.

19. Contact

Questions concerning these Terms should be addressed to info@zksf.org.