Structural Engineering Tools
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Terms of use and privacy notice

Draft for review by a lawyer before the public launch. Text in [brackets] still has to be completed.

Who we are

This website, structuralengineeringtools.com, is operated by Structural Engineering Tools, Switzerland. Contact: contact@structuralengineeringtools.com.

Terms of use

Version of 14 October 2026

1. What the service is

The website offers calculation tools ("modules") for structural engineering, based on the Swiss SIA standards. Some modules and features are free; others are part of the paid plans Basic, Pro and Expert, as described on the plan pages.

2. Professional responsibility

The modules support design and verification work. They do not replace the judgement of a qualified engineer. You remain fully responsible for the design, for the choice of the method, for the input values and for the interpretation and use of the results, including in calculation notes produced with the service. Before relying on a result, check that the module fits your case and that its results are plausible.

The modules quote clauses of standards but do not reproduce the standards. You need your own copy of the standards you apply.

3. Accounts

The free modules can be used without an account. The paid plans need an account in your name. Keep access to the e-mail address of your account secure: anyone who can read it can sign in.

An account is personal: one account per engineer. It may not be shared, lent or used by several people, and a company whose engineers use the service takes one account for each of them. An account can be used on one computer at a time. While it is in use on one computer, the service refuses it on another computer or from another internet connection and shows a message; it becomes available again when the first computer signs out, or 20 minutes after its last activity. We may suspend an account that is shared.

4. Paid plans, prices and payment

Prices are shown on the plan pages, in Swiss francs. They are final prices: value added tax is included where it applies. Payment is handled by Stripe Payments Europe Ltd.; we do not receive or store your card details. A plan is a subscription that renews automatically at the end of each period (one month or one year) until you cancel it. With yearly billing, the price corresponds to 9 monthly payments for 12 months of use.

We may change prices for future periods. We will tell you at least 30 days before a change applies to your subscription; you can cancel before then.

5. Cancellation, no refunds

You can cancel at any time in your account (Manage billing). The plan then stays active until the end of the period already paid and is not renewed.

Payments are not refunded, for monthly and for yearly periods alike, including when you cancel, change to a smaller plan or stop using the service before the end of a period. This does not affect a refund that mandatory law requires, or the case where we end a paid service ourselves (section 9).

6. Changes to the modules

We improve the modules continuously and may correct, change, replace or withdraw them, for example when a standard is revised. We decide which modules are free and which belong to which plan, and we may change this at any time: a free module may become part of a paid plan (Basic, Pro or Expert), and a module may move from one plan to another. A module that is part of your paid plan when you pay stays available to you until the end of that period.

7. Acceptable use

You may use the modules and the calculation notes for your own engineering work and that of your employer, including in documents you hand to clients and authorities. You may not copy, resell or redistribute the modules themselves, extract their code or content in bulk, query the calculation service automatically or from other software, circumvent the plan restrictions or the one-computer rule, or use the service in a way that harms it or other users.

8. Intellectual property

The modules, their code, texts, figures and the layout of the calculation notes belong to the operator. Your inputs and the results you produce are yours.

9. Availability and end of service

We aim for the service to be available at all times but cannot guarantee it. We may suspend an account that breaches these terms. If we end a paid service for reasons that are not yours, we refund the unused part of the period paid.

10. Liability

We prepare and check the modules with care (section "Checked before release" on the home page). To the extent permitted by law, we exclude liability for damage arising from the use of the service, in particular from errors in modules or results, and for indirect or consequential damage. This does not limit liability for damage caused intentionally or by gross negligence.

11. Changes to these terms

We may update these terms. The version in force is published on this page with its date. For substantial changes we inform account holders by e-mail at least 30 days in advance.

12. Law and jurisdiction

These terms are governed by Swiss law. The courts of Lausanne, canton of Vaud have jurisdiction, subject to mandatory consumer jurisdiction.

Privacy notice

Version of 14 October 2026

We collect as little personal data as the service needs. This notice explains what we process, why, and your rights, under the Swiss Federal Act on Data Protection (revFADP) and, for users in the European Union, the General Data Protection Regulation (GDPR).

Controller

Structural Engineering Tools. Contact for data protection: contact@structuralengineeringtools.com.

Your calculations

The modules calculate on our server. The values you enter are sent over an encrypted connection to the calculation service (run for us by Cloudflare), calculated, and the result is sent back to your browser. We do not store or log the values you enter or the results: they exist on the server only while the calculation runs. A module therefore needs an internet connection.

The title-block fields of the calculation note (project, author and similar) are remembered only in your own browser (local storage). When you leave a calculation to sign up or sign in, its inputs are kept there too, for at most 3 hours, so that the calculation is back in place when you return. Both can be cleared in your browser at any time.

What we process

  • Visiting the site: our hosting provider processes technical data such as IP address, browser type and the pages requested, to deliver the site and protect it against attacks. We do not use analytics or advertising cookies, and we do not track you across other sites.
  • "How did you hear about us?": the optional answer you choose when you create an account. We count only how many accounts gave each answer; the answer is not stored with your account. Legal basis: our legitimate interest in knowing which channels work, Art. 6(1)(f) GDPR.
  • Account: name, e-mail address, company (optional), country, language, date of acceptance of the terms, plan and subscription status, and the dates of sign-in. Purpose: providing the paid plans and signing you in. Legal basis (GDPR): contract, Art. 6(1)(b).
  • One computer at a time: for each account we record which session is using it, the internet address it is used from (for IPv6 addresses only the network part) and the time of its last activity, so that the account cannot be used on two computers at the same time. This record is replaced at each use and deleted when you sign out or delete the account. Legal basis: contract, Art. 6(1)(b) GDPR, and our legitimate interest in preventing shared accounts, Art. 6(1)(f).
  • Sign-in codes: to sign you in we send a 6-digit code by e-mail. We store only a cryptographic fingerprint of the code, for 10 minutes.
  • Payment: Stripe processes your payment details, billing address and tax number, and issues the invoices. We receive the status of your subscription and a customer reference, never your card number. Legal basis: contract, and our legal obligation to keep accounting records.
  • Security check: the sign-up and sign-in forms use Cloudflare Turnstile to tell people from automated abuse. Legal basis: our legitimate interest in protecting the service, Art. 6(1)(f) GDPR.
  • E-mails you send us: we use your message and address to answer you.

Cookies

We set one cookie, and only when you sign in: a session cookie that keeps you signed in for up to 30 days. It is strictly necessary for the account and contains no information about you, only a random reference. Signing out deletes it.

Service providers and transfers abroad

  • Cloudflare, Inc. (USA): hosting, content delivery, security, the calculation service, the account database (stored in Western Europe) and sending of sign-in e-mails.
  • Stripe Payments Europe Ltd. (Ireland) and its group companies: payments and invoices.

These providers may process data outside Switzerland and the EU, in particular in the USA. Transfers rely on the Swiss–US and EU–US Data Privacy Framework where the provider is certified, or on the standard contractual clauses approved by the Swiss Federal Data Protection and Information Commissioner and the European Commission.

How long we keep data

Account data: as long as the account exists; when you delete the account, it is removed from our database. Invoices and the payment records linked to them: 10 years, as Swiss law requires (Art. 958f CO). Technical logs: up to 30 days.

Your rights

You can ask for access to your data, its correction or deletion, and its transfer to you in a common format; under the GDPR you can also object to processing based on legitimate interest and ask for its restriction. You can delete your account yourself in your account page. Write to contact@structuralengineeringtools.com. You can lodge a complaint with the Swiss Federal Data Protection and Information Commissioner (FDPIC) or, in the EU, with the supervisory authority of your country.

Security

The site is served only over encrypted connections. There are no passwords to steal: sign-in works with single-use codes. Sessions and codes are stored as fingerprints, not in readable form. Access to our systems is protected by two-factor authentication.

Changes

We publish changes to this notice on this page with their date.