Getting Started

Install Responsive Tester, activate it on any page, and learn the toolbar, viewports, and keyboard shortcuts in a few minutes.

Install

Responsive Tester is a Chrome extension. Install it from the Chrome Web Store and pin it to your toolbar so the icon is always visible.

Open the Chrome Web Store listing and click Add to Chrome.
Click the puzzle-piece extensions icon in the toolbar, find Responsive Tester, and click the pin.

It runs in Chrome and other Chromium-based browsers such as Edge, Brave, Arc, and Vivaldi, on version 116 or later.

Activate It

Open any page and start Responsive Tester one of three ways:

Click the Responsive Tester icon in your toolbar.
Press Alt + Shift + V.
Right-click anywhere on the page and choose Preview in Responsive Viewer.

The current tab is replaced by the responsive viewer: a toolbar across the top and your device frames below it. Press the same shortcut again, or navigate the top frame away, to exit.

The toolbar runs along the top of the viewer and controls the whole session. From left to right it holds:

The address bar, showing the current URL of the frames.
A zoom slider that scales every frame together.
A layout toggle that switches the frames between a single scrolling row and a wrapped grid.
A theme toggle that cycles the viewer chrome through system, light, and dark.
Scroll sync and interaction sync toggles.
An add viewport button for presets and custom sizes.
An edit toggle that opens the live CSS editor.

Scroll sync is free. Interaction sync and the CSS editor are Pro, and their buttons stay locked until you start a trial or upgrade.

The Viewports

Each device is a live frame rendering the real page. Every frame shows the same page at all times, so following a link in one frame navigates all of them together.

Each frame has its own controls to rotate, resize by dragging its edges, expand it to fill the canvas, capture a screenshot, reorder it, or remove it. See Viewports & Devices for the full list.

Works on Any Site

Many sites block being shown inside a frame. Responsive Tester removes those frame-blocking response headers for the active tab only, for the length of the session, and restores normal behavior when you navigate away or close the tab. That lets you preview pages that other tools cannot load.

Keyboard Shortcuts

Alt + Shift + V toggles Responsive Tester on or off.
While the CSS editor is open, Cmd/Ctrl + Z undoes an edit and Cmd/Ctrl + Shift + Z redoes it.

Trial & Pro

The free features cover the whole preview workflow: multi-device viewports, scroll sync, site breakpoints, device presets and custom sizes, rotate, resize, zoom, overflow warnings, and screenshots. Pro adds interaction sync, live CSS editing, and change tracking with CSS export.

Every install starts with a 7-day Pro trial, no card required. After the trial, the free features stay free forever, and Pro is a one-time purchase with a 30-day money-back guarantee. See Trial & Licensing for the details.