Privacy policy
Last updated: 11 November 2026 · Version 1.0
ResponsiveKit shows a web page at several widths side by side, in one tab. It has no account, no ads, no analytics and no servers. ResponsiveKit itself sends nothing to anyone.
What it reads, and when
- The address of your current tab, only when you click the ResponsiveKit icon or press the shortcut (Alt+Shift+Y). It opens the viewer tab with that address.
- The pages you preview. The viewer loads them in frames, the same way your browser would load them. Your browser talks to those sites directly; ResponsiveKit doesn’t see or store their content.
- Inside the previewed frames only, a small script reads what it needs to keep the widths in step: the page’s address and title, scroll position, which link or button you clicked (as a position in the page, not its text), and the widths in the page’s own CSS (site breakpoints). It sends this only to the ResponsiveKit viewer in the same tab. On sites you allowed, Chrome loads this script in every frame, but it stops at once unless the frame sits directly in the ResponsiveKit viewer; it never reads or changes your normal tabs and never changes how a page looks.
- Local files (
file://) can’t be previewed in this version.
Site access (you decide, per site)
ResponsiveKit asks for no site access when you install it. The first time you preview a site, it shows Allow on {site} and Chrome asks you to confirm (“Read and change your data on {site}”). Access covers that site and its www / non-www twin. You can remove it any time in Chrome’s extension settings.
Changed response headers — inside the viewer only
Many sites tell browsers not to show them inside another page (the X-Frame-Options and Content-Security-Policy response headers). To preview them, ResponsiveKit removes these two headers, with these limits, enforced by Chrome:
- only for pages loaded in frames inside the ResponsiveKit viewer tab — never in your other tabs, never for normal page loads;
- only for the sites shown in that viewer at the moment (hiding a width removes its site when no other width shows it), and only on sites you allowed. Chrome matches a site together with its subdomains, and frames nested inside the previewed page are included too (for example an embedded video from an allowed subdomain);
- only while the viewer is open: the rule is removed when you close the viewer or leave it, and Chrome deletes it when it restarts.
What this means: inside the viewer, the previewed site’s own security policy (which, for example, limits which scripts may run) is switched off for that site. Preview sites you trust, and use Open in a window for anything sensitive. Signed-in pages may look signed out in the viewer, because Chrome doesn’t send most sign-in cookies to pages inside another page; Open in a window uses your normal session and changes nothing.
What is saved
Only your settings, on your device (chrome.storage.local): your widths (including custom widths and rotation), zoom, layout and the two sync switches. ResponsiveKit does not keep a list of the addresses you preview. The viewer tab’s own address contains the page you opened it for, so it appears in Chrome’s history and open tabs like any other tab.
What leaves your browser
- Nothing from ResponsiveKit.
- The previewed sites receive the requests your browser makes to them, as with any normal visit.
- Report a bug opens a Google Form with the extension name and version in the link (no page address). Google receives what you type only if you submit the form.
Not done
No selling or sharing of data, no tracking, no remote code, no use for advertising, credit or lending.