Terms of Service

Draft 1 · prepared 2026-09-08 · not reviewed by counsel · not in force

1 Who this is between

These terms are an agreement between [LEGAL ENTITY NAME], a [ENTITY TYPE] registered in [JURISDICTION OF INCORPORATION] at [REGISTERED ADDRESS], and you. In this document "we" and "us" mean that entity, and "you" means the person who accepts these terms. If you accept them on behalf of a firm, you are confirming that you are authorised to bind that firm, and "you" then means the firm as well.

You accept these terms by creating an account or by using the service. If you do not accept them, do not use it.

2 What CurveNumber is, and what it is not

CurveNumber is decision support software. It retrieves published data, applies published hydrologic methods to it, and produces a report that shows its working: where each figure came from, what was assumed, what that assumption is worth in the answer, and what a person changed and why.

CurveNumber is not engineering, and using it does not make us your engineer. We do not practise engineering, we do not offer engineering services, we do not review your design, and no engineer to client relationship is created between us by your use of the software. Nothing the software produces is a professional opinion, a certification, a stamped document or a substitute for the judgement of a qualified professional who has looked at the site.

Every figure the software produces requires independent verification before it is used for anything. That is not a formality: some values in the output are assumptions with no published source, and the report says which ones on its face precisely so that you can check them.

3 Your responsibility as the licensed professional

You are responsible for the design. If output from CurveNumber goes into a drawing, a calculation package or a submission that carries a professional seal, the person who applies that seal is responsible for the work, including for every figure taken from this software.

By using the service you agree that:

• you will verify the figures you rely on against the published sources the report cites, and against the requirements of the jurisdiction reviewing your work;
• you will read the assumptions the report prints and decide, for your site, whether each one is acceptable, rather than accepting them because the software offered them;
• you understand that the published tables transcribed into this software have not been independently checked against the source documents, that the software records this on the face of every report that uses them, and that checking them is part of the verification described above;
• you will not present output from this software as an engineering opinion of ours, and will not use our name or any report identifier to suggest that we approved your design;
• you hold whatever licence or registration your jurisdiction requires for the work you are doing, and you will comply with the rules of professional conduct that apply to you.

We cannot check any of the above, and we do not try to. It is stated here because it is the honest description of how this software has to be used.

4 Accounts and keys

An account needs an email address, and you may give an organisation name. Your account is issued an API key, which is shown once and stored by us only as a hash, so we cannot recover it for you and can only issue a new one.

Keep the key secret. Anything done with your key is treated as done by you, including computations that consume free sites or spend credit. Tell us promptly at [SECURITY CONTACT EMAIL] if you believe your key has been disclosed, and we will revoke it and issue another.

You are responsible for the accuracy of the account details you give us, and for keeping the email address current, because it is how we reach you about your account.

5 What you pay

The first two sites on an account are free. After that, each site costs USD 100. A site is charged once, the first time it is computed, and not when it is created; recomputing a site you have already paid for costs nothing further. Retrieving public data for a site costs nothing. The stateless quick check costs nothing and requires no account.

There is no subscription and no recurring charge. Prices are in United States dollars and do not include any sales, use, value added or similar tax, which is yours to pay if it applies.

Payment is currently arranged by invoice. You tell us how much credit you want, we invoice you, and the credit is added to your account when the invoice is paid. Credit is spent one site at a time and does not expire unless your account is closed under section 13.

Refunds: [REFUND POSITION TO BE DECIDED]. We would rather leave this blank than write a policy the business has not decided on.

We may change our prices. A change does not affect credit you have already bought, and we will publish the new price on this website before it applies.

6 Public datasets we do not control

CurveNumber reads from public data services run by other people, including the United States Department of Agriculture, the United States Geological Survey, the National Oceanic and Atmospheric Administration and the United States Census Bureau. They are listed with what each one supplies on our privacy page.

We do not run those services, we do not control them, and we have no agreement with them that guarantees anything. So:

• we do not warrant that the data they publish is accurate, current, complete or fit for your purpose;
• we do not warrant that they will be available, and they do go down, change their interfaces, republish with different values, or stop covering an area;
• where a service is unreachable, the software tells you that it was unreachable rather than substituting a value, and a computation may be delayed or refused as a result;
• where a dataset is revised, a figure derived from it may differ from one derived earlier. The software records what it retrieved, when, and the response it got, so that a difference can be traced rather than argued about.

The data those services publish is theirs and is subject to their own terms. Where a service imposes conditions on how its data may be used, those conditions apply to you as well as to us.

7 When the software refuses to answer

CurveNumber is built to withhold a figure when it cannot honestly derive one. It refuses to give a curve number to open water, it refuses to guess a hydrologic soil group that the soil survey does not publish, and it will not produce a headline result while a material share of your site is unresolved.

Those refusals are intended behaviour and are not defects. They come with the reason and with what you would have to supply instead. We are not liable for a refusal, and a refused site is still charged if it was computed, because the work of retrieval and computation was done and the answer it produced is the honest one.

8 Your data, and who owns it

Your data means what you put in: your account details, project and site names, client and jurisdiction names, site boundaries, addresses, segments, design parameters, practice details, the reasons you write when you override a value, and the results computed from those.

You own it. Nothing in these terms transfers ownership of it to us.

You give us permission to store it, process it and transmit it, only as far as is needed to run the service for you: to hold your projects and sites, to send a boundary or an address to the public data services so that data can be derived, to compute results, to generate reports, and to keep the audit record that gives those reports their value. That permission ends when the data is deleted, except for backups, which age out on our normal cycle.

We will not sell your data, and we will not share it with anyone else except the public data services described on the privacy page, the infrastructure providers who host the service, and anyone we are legally required to disclose it to. If we are required to disclose it, we will tell you unless we are prohibited from doing so.

We may look at your data when you ask us to help with a problem, or when we have to in order to keep the service running or to investigate misuse. [CONFIRM WHETHER AGGREGATE, NON-IDENTIFYING USAGE STATISTICS MAY BE USED TO IMPROVE THE PRODUCT].

You can export your reports and your audit trail from the service at any time while your account is open.

9 Our material, and what you may do with it

The software, this website and the way the reports are put together are ours. We give you permission to use the service, and to use, keep and hand on the reports it produces for you, including to your client and to a reviewing authority. That permission is not exclusive and is not transferable except along with the report itself.

The defaults registry, which states what each assumption is worth and what would displace it, is published free and is meant to be cited. You may quote it, including in a calculation package or a submission, under [LICENCE FOR THE REGISTRY, FOR EXAMPLE CC BY 4.0].

You may not copy the software, take it apart to rebuild it, resell access to it, or use it to build a competing product. You may not remove or alter the provenance marks, the citations, the identifiers or the disclaimer on a report, because a report without them misrepresents what it is.

10 Availability

We do not promise that the service will be available at any particular time or to any particular standard. This is pre-launch software running on modest infrastructure, and it may be interrupted for maintenance, for repairs, or by a failure of something we depend on.

The service is provided as it is, without any warranty beyond what the law requires us to give. In particular we do not warrant that it is fit for a particular purpose, that it will meet the requirements of any jurisdiction, or that its output is free of error.

[FOR THE LAWYER: this disclaimer and section 11 are written in plain sentences rather than in capital letters. Some United States jurisdictions expect a disclaimer of implied warranties to be conspicuous. Please confirm that headings and plain language are sufficient here, or tell us what formatting you want instead.]

11 Limits on what we are liable for

This section limits what you can recover from us. Read it.

We are not liable for your design. You are responsible for the engineering, and we are not liable for any loss arising from a design, a submission, a drawing or a decision that used output from this software, including where the output was wrong.

We are not liable for indirect loss. We are not liable for lost profit, lost business, lost opportunity, loss of goodwill, project delay, redesign cost, rework, the cost of a resubmission, a regulatory penalty, or any indirect or consequential loss, even if we were told that it was possible.

There is a cap. Our total liability to you for everything connected with this agreement is limited to the greater of the amount you have actually paid us in the twelve months before the event giving rise to the claim, and [CAP FOR USERS WHO HAVE PAID US NOTHING, FOR EXAMPLE USD 100].

What we do not limit. Nothing here limits our liability for death or personal injury caused by our negligence, for fraud or fraudulent misrepresentation, or for anything else that cannot be limited under the law that applies to this agreement.

These limits apply however the claim is framed, in contract, in tort including negligence, or otherwise. They reflect that this software costs a hundred dollars a site and is used inside work that is insured, sealed and reviewed by professionals.

12 Claims arising from your use

If someone brings a claim against us because of how you used the service, including a claim arising from a design or submission of yours, or from your breach of these terms, you will defend us against it and cover the reasonable costs, damages and legal fees we incur. We will tell you promptly about any such claim, let you control the defence of it so long as you do not settle it in a way that admits fault on our part or costs us money, and cooperate with you at your expense.

13 Ending this agreement

You can stop using the service at any time and can close your account by writing to us. Unused credit is [REFUNDABLE OR NOT, TO MATCH SECTION 5].

We can suspend or close your account if you break these terms, if you use the service in a way that damages it or another user, if we are required to by law, or if you have not logged in for [DORMANCY PERIOD, FOR EXAMPLE 24 MONTHS]. Except where the law or a serious breach makes it impossible, we will give you notice first and a chance to put it right.

We may also stop offering the service. If we do, we will give you at least [NOTICE PERIOD, FOR EXAMPLE 60 DAYS] notice by email, you will be able to export everything during that period, and we will refund credit you have bought and not spent.

When an account closes, you have [EXPORT WINDOW, FOR EXAMPLE 30 DAYS] to export your data. After that we delete it from the live service, and it ages out of backups on our normal cycle. Deleted data cannot be recovered. Reports you have already downloaded remain yours and are unaffected.

Sections 2, 3, 8, 9, 11, 12, 15 and 16 continue to apply after this agreement ends, along with any obligation to pay for something already used.

14 Changes to these terms

We may change these terms. If a change materially affects you, we will email the address on your account at least [NOTICE PERIOD, FOR EXAMPLE 30 DAYS] before it takes effect, and we will keep the previous version available so you can see what changed. Continuing to use the service after a change takes effect means you accept it. If you do not accept it, close your account, and we will refund credit you have bought and not spent.

15 Law, disputes and notices

This agreement is governed by the law of [GOVERNING LAW, JURISDICTION], and the courts of [COURTS, JURISDICTION] have exclusive jurisdiction over any dispute, except that either of us may seek an injunction anywhere it is needed.

[DECIDE WHETHER TO REQUIRE INFORMAL RESOLUTION FIRST, AND WHETHER TO INCLUDE ARBITRATION AND A CLASS ACTION WAIVER. THEY HAVE REAL CONSEQUENCES FOR CUSTOMERS AND SHOULD BE A DELIBERATE CHOICE, NOT A TEMPLATE DEFAULT.]

Formal notices to us go to [NOTICE ADDRESS: POSTAL ADDRESS] and to [NOTICE EMAIL ADDRESS]. Notices to you go to the email address on your account. A notice by email counts as given on the day it is sent, unless it bounces.

16 The rest

These terms, together with the privacy notice, are the whole agreement between us about the service, and they replace anything said before.

If a court finds part of this unenforceable, the rest still applies, and that part is read as narrowly as it needs to be to become enforceable.

If we do not enforce something straight away, we have not given up the right to enforce it later.

You may not transfer this agreement without our written consent. We may transfer it to a company that acquires our business, and we will tell you if we do.

Nobody other than you and us has any right to enforce these terms.

Neither of us is liable for a failure caused by something genuinely outside our control, but this does not excuse a failure to pay.