Formspill privacy policy

Effective date: 19 October 2026 · Publisher: Mozilor · Contact: research@mozilor.com

Formspill is a browser extension that shows you who receives what you type into a website's forms. This policy explains what the extension handles and what it does with it.

In short: Formspill does not collect, send, sell or share any of your data. Everything it does happens inside your browser.

What Formspill looks at

When you click the Formspill icon on a page, the extension reads that page in your browser:

• the forms on the page and their fields (labels, field names and types), to tell which ask for personal details;
• the addresses of scripts and embedded frames from other companies, to name who runs code on the page.

It reads the page only when you click the icon on it. It does not read pages in the background, and it does not read what you have typed into a form.

To see forms placed lower down the page, Formspill asks embedded frames that would load only when you scroll to them (maps, videos, booking or sign-up widgets) to load straight away. Those frames come from the website and the companies it embeds, so they may set their own cookies, as they would if you scrolled down. Formspill changes nothing else on the page.

The full check

When you choose Check where my data goes, Formspill opens the same page in a separate window, types made-up details into its forms (for example an email address ending in .invalid, which cannot belong to anyone), and watches where those made-up details are sent. Every request carrying them is stopped inside the browser, and so is every request whose content Formspill cannot read once they have been typed, so nothing is submitted to the website or anyone else. Your own details are never typed.

• By default the full check runs in a private (incognito) window, so the website does not see your cookies or logins, and what it stores during the check is deleted when the window closes. Chrome requires you to switch on “Allow in Incognito” for this. The check does not start while another private window is open, because Chrome's private windows share cookies.
• If you choose to run it in your normal profile instead (for pages behind your login), the check runs with your own cookies and logins, so:
  • the website sees your cookies as it would on any visit, and any cookie-banner choice the check makes is remembered by the site;
  • to find where the made-up details were stored, Formspill reads, inside your browser, the cookies of the sites the page contacted during the check. It keeps only those that contain the made-up details, and deletes them. It never sends or stores your other cookies;
  • it also deletes the website's stored items (local and session storage) that contain the made-up details. Other kinds of site storage (such as databases a site keeps in your browser) are not cleaned, so a site may still hold made-up details there;
  • background scripts the site runs for all of its open tabs (service workers) are watched during the check, and requests they make in that time are checked and stopped like the page's own.
• During the full check the website receives a normal page visit from your browser, as if you had opened the page yourself. Chrome shows a bar saying Formspill is debugging the browser while the check runs; cancelling it stops the check at once.

What Formspill stores, and for how long

• Results of your checks are kept in your browser's session storage so the sidebar and report can show them. They include the page address, the forms found, the made-up details used, and where they were sent. At most the 20 most recent results are kept, and all of them are deleted when you close the browser. A result is removed from the sidebar when you leave the page it describes.
• Fields you mark as personal (“Asks for something personal” on a field Formspill could not identify) are kept in the same session storage, as the field's name and position on the page, so the full check can follow them. They are removed when you leave the page and deleted when you close the browser. What you typed is never stored, because Formspill never reads it.
• When you check a page again with the cookie banner rejected, the earlier result with it accepted is kept alongside, so the sidebar can show what rejecting changed. Both follow the rules above.
• One setting (whether full checks use a private window or your normal profile) is kept in your browser's local storage until you change it or remove the extension.

Nothing else is stored. There are no accounts.

What Formspill never does

• It does not send any data to Mozilor or to anyone else. The extension has no server and makes no network requests of its own.
• It does not use analytics, tracking, advertising or crash reporting.
• It does not sell, rent, share or transfer data, and does not use it for anything other than showing you the result.
• It does not load or run code from the internet; all of its code is included in the extension.

Permissions and why they are needed

Limited use

Formspill's use of information received from Chrome APIs adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements.

Children

Formspill is not directed at children and does not knowingly handle information from children.

Changes

If this policy changes, the new version will be published at this address with a new effective date. Changes that affect what the extension does with data will also be described in the extension's release notes.

Contact

Questions about this policy: research@mozilor.com.