The problem
Checking a page at different sizes or in different states usually means doing everything more than once — the same clicks, scrolling, typing and navigation, repeated in each window just to compare the results. Keeping several windows in step by hand is slow, tedious and easy to get subtly wrong.
What it does
Dual mirrors one set of interactions across every participating Chrome window in real time:
- Interact once, mirror everywhere — clicks, typing, scrolling, navigation, hover and focus are replicated across windows as you go.
- Made for responsive testing — line windows up at different viewport sizes and watch the same page behave across them side by side.
- Pick exactly which tabs take part — toggle each window in or out from the toolbar.
- Per-site rules — choose which events sync, and map URLs across domains to compare staging against production.
Under the hood
A Chrome extension built on Manifest V3. A background service worker coordinates a set of content scripts that capture what you do in one window and replay it in the others over long-lived message ports, with your preferences held in the browser’s own storage. Element matching is robust enough to reach into shadow DOM and across iframes. See the privacy policy for exactly what it does and doesn’t touch.
Status
Dual is in private beta. We’re polishing the experience with a small group of users before a wider release.
Want to try it? Get in touch.