The short version
The calculator runs entirely in your browser. Expressions you type are parsed, differentiated, simplified and plotted on your own device, and are never transmitted to us.
What is stored on your device
Two things are kept in your browser's local storage: your recent expressions, so the Recent row survives a reload, and your light or dark theme choice. Both live only on the device you are using. Clearing your browser's site data removes them, and nothing is copied anywhere first.
What we do not collect
There are no advertising trackers, no analytics profiles built about you, and no accounts to create. We do not sell data, because we do not gather it.
Third-party resources
Two resources are requested from content delivery networks: the web fonts from Google Fonts and the MathJax typesetting library from cdnjs. Those requests expose your IP address to those providers in the ordinary way any web request does. No identifiers are attached by us.
The contact form
If you use the contact page, the name, email address and message you type are sent to our form provider so the message can be delivered to us. They are used to answer you and nothing else. Writing directly to hello@derivativescalculator.org avoids the intermediary entirely.
Children
The site is suitable for students of any age and does not knowingly collect personal information from anyone, including children.
Your rights
Because we hold no profile about you, there is normally nothing to request or erase. If you have written to us, you can ask us to delete that correspondence at any time.
Changes
This policy may be updated; the date above shows the latest revision.