Privacy policy

Last updated: November 13, 2026

This policy explains what information Sheetwise Engineering LLC ("we") and MathSheet handle, where it goes and how long it is kept. It matches section 11 of the license agreement (version 2.1).

Your worksheets stay on your computer

Your worksheets, calculations, autosaves, templates and settings are stored only on your computer, or wherever you choose to save them. MathSheet does not send them to us or to anyone else.

License activation (keys bought online)

If you use a license key bought from our online shop, MathSheet connects to the license service of our reseller, Lemon Squeezy:

• Once, when you enter the key. MathSheet sends the license key and this computer's code.
• About once every 30 days, when the computer is online. MathSheet sends the license key and the activation number the service gave it, to check that the license is still valid.
• If the license is moved off the computer. The same key and activation number.

Like any internet connection, these requests also show the service your computer's internet (IP) address. Nothing else is sent: no worksheets, no file names, no results.

If the computer is offline or the service cannot be reached, MathSheet keeps working. A license is removed from a computer only if the service clearly answers that it is no longer valid (for example after a refund) on two checks at least 3 days apart.

The computer code

The computer code is a short code, for example K7Q2-9MXD, calculated by a one-way function from the identifier Windows creates when it is installed (or, if that is missing, from the computer's name). It lets one license work on one computer. It does not contain your name or your files. Because it stays the same for that Windows installation, it can identify a computer, so we treat it as personal information.

What MathSheet keeps on your computer

• After activation: the license key, the activation number, the buyer's name and e-mail address and the product name, as returned by the license service. They are protected by Windows for your Windows user account, so MathSheet can show who it is licensed to and work offline.
• The dates MathSheet was first and last started, and the date you accepted the license agreement.
• If MathSheet has a fault, an error log in your user folder. It is not sent anywhere; you may choose to e-mail it to us.

Removing MathSheet leaves the license and these dates in place, so installing it again needs no new key. To remove them as well, delete the folder %LOCALAPPDATA%\MathSheet and the registry key HKEY_CURRENT_USER\Software\MathSheet. MathSheet will then need its license key again.

License keys we make for one computer

If we make a license key for you by e-mail, you send us your computer code, and the key contains the name and e-mail address you give us. MathSheet checks such a key on your computer without the internet.

Buying MathSheet

Purchases are handled by Lemon Squeezy as merchant of record. They collect your name, e-mail address, billing details and payment information to process the order, under their own privacy policy (lemonsqueezy.com/privacy). We receive your name, e-mail address, country and order details so we can support you, and we can see when and on which computer code each license key was activated. We never see your full card number.

E-mails you send us

Our support e-mail is hosted by Google (Gmail). If you e-mail us, we keep your message and address to answer you. We do not sell or share it.

Launch news e-mails

If you sign up for launch news on this website, your e-mail address (and first name, if you give it) is kept in our e-mail list at Lemon Squeezy, which sends the e-mails for us, under its own privacy policy. We use it only to tell you about MathSheet: when it launches, and now and then with news about it. Every e-mail has an unsubscribe link, or e-mail sheetwiseengllc@gmail.com and we will remove you. We never sell or share your address.

This website

This website uses no cookies, analytics or advertising trackers. Its one script only switches the Buy, Download and sign-up buttons on and shows pictures full size. The site is hosted on GitHub Pages; GitHub may keep standard server logs (such as IP addresses) for security. The Buy button takes you to the Lemon Squeezy checkout, which has its own policy.

Other software MathSheet uses

On Windows, MathSheet shows its pages with the Microsoft Edge WebView2 Runtime, which is part of Windows and is covered by Microsoft's own privacy statement. Web links in MathSheet open in your normal web browser.

How long information is kept

• On your computer: until you delete it (see above).
• At Lemon Squeezy: under Lemon Squeezy's own policy.
• Our order records: as long as tax law requires.
• Support e-mails: as long as needed to support your license.

Your choices

You can ask what information we hold about you, or ask us to delete it, by e-mailing sheetwiseengllc@gmail.com. Deleting the activation record of a license you still use means the key has to be activated again.

Children

MathSheet is not aimed at children under 13, and we do not knowingly collect their information.

Changes

If we change this policy, we will update the date at the top of this page.