Z-Thru privacy policy

Effective 2026-09-23. Applies to the Z-Thru Chrome extension.

Summary: Z-Thru works entirely on your computer. It sends nothing anywhere: no page content, file paths, results, analytics, or telemetry. It has no accounts, servers, or AI services.

What Z-Thru reads

When you choose Open inspector on a local HTML file, Z-Thru loads its inspector into that tab. When you choose Check page, it reads that page's current content in your browser to test it against accessibility rules. It reads nothing before you ask, and never from tabs you have not opened it on.

What Z-Thru stores, and where

Z-Thru stores the following in Chrome's extension storage (chrome.storage.local) on this computer only. It is not synced to your Google account or other devices.

Latest results for each file you check: the file's address (its file:/// path), the check time, and each detected issue. An issue records its rule, severity, a CSS selector for the element, the built-in guidance text, and the checker's short description, which can include attribute values or colors from the page. For contrast issues, the measured text and background colors, ratio, and font size are stored too. Your Needs human review answers, the viewport size, whether the check scrolled through the page and how many screens it covered, and the checker's version and rule set are also stored.
Preferences: inspector placement and text size.

Z-Thru does not store the page's HTML, text you type into forms, screenshots, or your browsing history. Results for at most 50 files, up to about 5 MB, are kept; when full, Z-Thru tells you instead of deleting older results.

Deleting your data

One file: in the inspector, under Saved results, choose Delete saved results for this file.
Everything: in the toolbar popup, choose Clear all saved results and confirm.
Uninstalling Z-Thru removes all of its stored data.

Permissions

activeTab: access only the tab where you click the Z-Thru icon, at that moment.
scripting: load the inspector into that tab when you ask.
storage: keep results and preferences on this computer.
Access to file:///*: check HTML files opened from your computer. This only works after you turn on Allow access to file URLs in Chrome.

Z-Thru does not request access to websites (http or https), your browsing history, downloads, or any other data.

Z-Thru does not sell, share, or transfer any data. Nothing leaves your computer.

Changes and contact