The script inside a workbook reads and edits the one spreadsheet you copied, and nothing else. It does not read your email, it does not open other files in your Drive, and it does not transmit anything to an external server. There is no server. It runs inside your own Google account, under your own permissions.
This means the numbers you put into a savings plan or a payoff tracker are never visible to us at any point, including when you contact support.
When you buy, we hold the details needed to complete and support that order: your email address, the item bought, and the record of the transaction. Card details are handled by the payment processor and never reach this site.
When you use a contact form, we hold what you typed into it, so that a reply can be written. That is the name, email address and message you submitted, and nothing gathered in the background.
The site runs on WordPress with a caching layer, which sets functional cookies needed for the shop and the cart to work. There is no advertising network on this site and no cross site tracking.
A hosting provider stores the site and its database. A payment processor handles payment and holds the transaction record under its own privacy policy. An email service delivers messages such as order confirmations and support replies. Google operates Sheets and Drive, where your workbook lives, under Google's own terms and privacy policy.
Your details are not sold, rented, or shared with anyone for marketing.
Order records are kept as long as tax and accounting rules require. Support messages are kept while they are useful for answering follow up questions, then deleted. You can ask for either to be removed sooner, subject to those legal retention rules.
You can ask what is held about you, ask for it to be corrected, ask for it to be deleted, and ask for a copy. Send the request through the support page from the email address concerned, and it will be handled without argument.
If this policy changes in a way that matters, the change will be described here rather than buried in a version number.