Privacy Policy

Amazon Book Sales Calculator, browser extension · Effective 2 October 2026

In short

• The extension collects no personal data and sends nothing from your browser to us or to anyone else.
• It reads only the Amazon.com book page you open, inside your browser, to show the estimate.
• It saves only your calculator inputs and a small counter for the rating prompt, in your browser's extension storage.
• No account, no sign-in, no analytics, no ads, no cookies.

What the extension reads

On Amazon.com book pages (addresses with /dp/ or /gp/product/), the extension reads the text that is already visible on the page: the sales rank, the format, the price, the Kindle Unlimited label, the print length, the file size and the publisher. It uses them only to show the panel with the estimate on that page. This happens on your device. The extension does not store this page data, keeps no history of the books you view, and does not send it anywhere.

It does not run on other websites and does not read other pages.

What the extension saves

The extension uses chrome.storage.sync for two things:

• the values you type into the manual calculator (rank, format, price, royalty rate, file size, printing cost), so they are still there the next time you open it;
• a counter for the rating prompt: how many times a result was shown, how many times you closed the prompt, and whether you clicked a star.

If Chrome sync is on in your browser profile, your browser syncs these values between your own devices through your Google account, under Google's privacy policy. We never receive them. Removing the extension deletes them.

Network requests

The extension makes no network requests of its own. It loads no remote code and no remote data. Links in the extension open only when you click them:

• Report a problem opens your email app with our address. You decide what to write and whether to send it.
• The rating stars open the extension's reviews page in the Chrome Web Store.

Our web pages

After you install the extension, it opens a welcome page on gavrysh.dev. After you remove it, your browser opens a page on gavrysh.dev that asks one optional question: why did you uninstall? These pages are static. They set no cookies and contain no analytics or tracking code. Our host, Cloudflare, processes technical request data such as IP addresses to deliver and protect the pages.

If you answer the uninstall question, your answer is stored in a Google Form that only we can read. The form does not ask for your name or email address; please do not include personal information in your answer. We use the answers only to improve the extension.

Permissions

• Access to Amazon.com book pages: to read the rank and price on the page you open and show the panel there.
• scripting: to show the panel in Amazon.com book tabs that were already open when you installed or updated the extension, without reloading them.
• storage: to save your calculator inputs and the rating-prompt counter, as described above.

Sharing and sale

We do not collect user data, so we do not sell, share, or transfer it. The use of information received from Chrome APIs adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements.

Changes

If a future version changes what the extension reads, saves, or sends, we will update this page before that version is published and change the effective date above.

Contact

Questions about privacy: bookcalc@gavrysh.dev