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Privacy Policy

Last updated: 6 October 2026

MotionConvert (operated by Solvera, KvK 97843776, VAT NL005292567B81, Mijdrecht, the Netherlands) is committed to protecting your privacy and handling your personal data in accordance with the General Data Protection Regulation (GDPR) and other applicable EU and Dutch law. This page explains what we collect, why, and what your rights are.

1. Data Controller

The data controller for personal data processed via motionconvert.com is Solvera, registered in the Netherlands under KvK number 97843776. For any privacy-related question or request you can reach us at info@motionconvert.com.

2. What Data We Collect

  • Account data: your email address and a hashed password when you sign up, plus an email-verification flag and timestamps.
  • Profile preferences: your selected tier (free/pro/expert), theme, unit system, preferred units, rounding mode and decimals, and whether auto-save is enabled.
  • Consent log: for each opt-in or opt-out you record we keep an append-only row capturing the event (opt-in / opt-out / soft opt-in), the purpose ("product updates" or "newsletter"), the source (signup form, settings page, unsubscribe link), the lawful basis, the policy version you agreed to, and the IP address and user-agent of the request. Email-keyed and retained indefinitely so an opt-out is honoured for life (see §5 and §11).
  • Saved content: the projects, components and tool configurations (e.g. motor specs, gear ratios, statusword values) you create or save, including any share-link UUIDs you generate.
  • Billing data: for paying users, your Stripe customer ID, subscription ID, and invoice records (amounts, currency, billing period, hosted invoice URL). Card details are processed and stored by Stripe; we never see or store them.
  • API keys: if you create one, we store a hash of the key (not the key itself), a short prefix, a name you choose, and the creation timestamp.
  • Email-results requests: if you use the "Email Results" feature without an account, we use the email address you enter solely to deliver that one message; we do not add it to any list. A normalized form of the address and your IP address are kept in our cache for 24 hours to enforce abuse limits.
  • Technical data: your IP address (used for rate-limiting and abuse prevention), basic request metadata, and standard server logs.
  • Cookies: strictly-necessary cookies always, and Google Analytics cookies only if you accept them (see §6).

3. How We Use Your Data and Legal Bases

  • To provide the service: creating your account, saving your configurations, running calculations, and serving pages. Legal basis: performance of a contract (GDPR Art. 6(1)(b)).
  • To process payments and manage subscriptions: handling Stripe checkout, subscription changes, and invoice records. Legal basis: performance of a contract and compliance with our legal obligations (Art. 6(1)(b) and (c)).
  • To send transactional email: email-address verification, password resets, billing notices, and the one-time emailed results you explicitly request. Legal basis: performance of a contract and, for the email-results feature, your explicit consent (Art. 6(1)(a)).
  • To prevent abuse and keep the service secure: rate-limiting, blocking malicious traffic, and keeping operational logs. Legal basis: our legitimate interest in protecting the service and our users (Art. 6(1)(f)).
  • To comply with legal obligations: for example, retaining invoice data for the period required by Dutch tax law. Legal basis: legal obligation (Art. 6(1)(c)).
  • To send a small number of product-update emails: see §11 for the full description, audiences, and opt-out. Legal bases: our legitimate interest under the soft opt-in for paying customers (Art. 6(1)(f) read with recital 47 and ePrivacy Art. 13(2)), and your explicit consent for free-tier users (Art. 6(1)(a)).

4. Data Sharing and Processors

We do not sell or rent your personal data. We share data only with the processors we need to run the service:

  • Stripe: payment processing, subscription management, and invoicing. Stripe acts as an independent controller for payment data and may transfer data to the United States under EU Standard Contractual Clauses.
  • DigitalOcean: server hosting in the EU.
  • Our email/SMTP provider: delivery of transactional email (verification, password reset, billing, results).
  • Let's Encrypt: issuance of TLS certificates for the domain.
  • Google: website analytics (Google Analytics via Google Tag Manager), and only for visitors who accept it. See §6.

We use no advertising or ad-targeting services.

5. Data Retention

  • Account, profile, projects and configurations: kept for as long as your account exists. If you delete your account, this data is removed within 30 days, except where we are legally required to keep it.
  • Accounts never confirmed: if the email address of a new account is not confirmed within 14 days, the account is deleted automatically.
  • Invoice and billing records: retained for 7 years to comply with Dutch tax law, even after account deletion.
  • Email-results rate-limit data: the recipient address and IP are retained in our cache for at most 24 hours for abuse prevention, then automatically deleted.
  • Server logs: kept for a short operational period (typically up to 30 days) and then rotated out.
  • Anonymous shared configurations: share links you create without an account expire and are deleted automatically after 12 months without being opened. Each time the link is opened this period resets, so links in active use are kept; only links left unopened for a full year are removed. Configurations saved to a logged-in account are not subject to this cap and are kept until you delete them or close your account.
  • Consent log: every opt-in and opt-out we record (see §2) is kept indefinitely so we can honour your opt-out even after account deletion or re-signup, and so we can demonstrate consent under GDPR Art. 7(1) on a regulatory challenge. This is a legal obligation and cannot be waived.

6. Cookies

These strictly-necessary cookies are always set. Under the EU ePrivacy rules they do not require consent, and the site cannot work without them:

  • sessionid: keeps you logged in and preserves your session.
  • csrftoken: protects forms against cross-site request forgery.

We also use Google Analytics, loaded through Google Tag Manager, to understand how the site is used: which pages people open and where they arrived from. It runs only if you accept it. If you decline, nothing from Google is loaded at all and no analytics cookie is set. You can change your mind at any time using "Cookie settings" at the bottom of any page; withdrawing takes effect immediately, not at your next visit.

If you accept, Google sets cookies (_ga and _ga_*) holding a random identifier so a repeat visit can be recognised as the same browser. We never send Google your name, your email address, or anything you save in the tools. Advertising and personalisation signals are switched off, and we run no advertising cookies.

If you have accepted analytics when you buy a plan, we store that same random identifier with your account and report the payment (the plan, the amount and the currency) to Google Analytics against it, including the automatic renewals of that subscription. A failed payment and the end of a subscription are reported the same way. This is how we can see which parts of the site lead to paying customers. We never send your name or email address with it. If you did not accept, nothing about your payments is sent to Google. Declining through "Cookie settings" deletes the analytics cookies and the stored identifier, which stops this too, renewals included.

Separately, our own server counts how often each page is opened per day, together with the website a visitor arrived from (only its domain, such as linkedin.com). This count uses no cookies and stores no IP address or anything else that could identify you, so it needs no consent.

7. International Transfers

Your data is primarily processed within the EU/EEA. Some processors (notably Stripe and, if you accept analytics, Google) may transfer data to the United States; in those cases the transfer is covered by the EU Standard Contractual Clauses or another valid GDPR transfer mechanism.

8. Your Rights

Under the GDPR you have the right to:

  • access the personal data we hold about you;
  • correct inaccurate or incomplete data;
  • request deletion of your data ("right to be forgotten"), subject to our legal retention obligations;
  • restrict or object to certain processing;
  • receive your data in a portable format;
  • withdraw any consent you have given, at any time, without affecting prior processing;
  • lodge a complaint with the Dutch Data Protection Authority (Autoriteit Persoonsgegevens) or your local supervisory authority.

To exercise any of these rights, email info@motionconvert.com. We will respond within one month.

9. Security

We use appropriate technical and organisational measures to protect your data, including TLS encryption in transit, hashed passwords and API keys, restrictive Content-Security-Policy and security headers, isolated rate-limit storage, and limited operational access. No method of transmission or storage is 100% secure, but we work to keep risks low.

10. Children

MotionConvert is not directed at children under 16. If you are under 16, please do not create an account or send us personal data. If we learn that we have collected data from a child without verified parental consent, we will delete it.

11. Marketing Communications

We send marketing email only for the purposes you have consented to, and each is a separate choice. There are two. Product updates: once or a few times per year, a short email about new MotionConvert tools, pages or articles, all closely related to the engineering calculators you already use. Newsletter: about every two weeks, an email with a new article or a newsletter issue. You can subscribe with the optional box when you create an account, in account settings, or at /newsletter/ with or without an account. You are only subscribed once you click the confirmation link we email you; through /newsletter/, we store nothing about you until then. Subscribing to one does not subscribe you to the other. Any new purpose we introduce (for example beta-program invitations or surveys) will likewise be a separate, opt-in choice. We do not send promotional email about unrelated products, third-party offers, or anything outside the scope you have agreed to.

Whether you receive product-update emails depends on which group you are in:

  • Paying customers (Pro, Expert, Early Bird): covered by the soft opt-in under recital 47 of the GDPR and Article 13(2) of the ePrivacy Directive: you bought a similar product, you are notified at signup that you may receive these messages, and every email contains a one-click unsubscribe link. You can also opt out at any time in your account settings. Legal basis: Art. 6(1)(f), our legitimate interest in keeping customers informed about similar products and services we provide.
  • Free-tier registered users: only emailed if you have actively opted in, in account settings. Accounts created before 24 September 2026 could also opt in with a box at signup; that box now subscribes you to the newsletter instead. Neither is ever pre-selected. You can withdraw consent at any time, as easily as you gave it. Legal basis: Art. 6(1)(a), your explicit consent.
  • Anonymous "Email Results" recipients: never receive marketing email from us. The address you (or someone else) entered into the Email Results form is used only to deliver that one specific calculation result and is purged from our cache within 24 hours. Recipients are not added to any list under any circumstance.

We keep an append-only consent log of every opt-in and opt-out we record (event, purpose, timestamp, source, the policy version you agreed to, and the IP address and user-agent of the request). This log is the legal record we would produce on a regulatory challenge under GDPR Article 7(1) and is retained indefinitely so that an opt-out cannot be undone by closing and re-opening an account under the same address.

Unsubscribing is always one click in any product-update or newsletter email and is honoured before any further send. None of the above affects transactional email (account verification, password reset, billing notices, the Email Results message you explicitly request). Those are required to operate the service and cannot be unsubscribed from while you have an active account.

12. Changes to This Policy

We may update this Privacy Policy as our service evolves. The latest version is always published on this page, with the "Last updated" date at the top.

13. Contact

For privacy questions, requests, or complaints, contact us at info@motionconvert.com.