ViewportStudio

A focused responsive testing workspace with automatic previews and synchronized interactions.

Test responsive layouts across phones, tablets, and desktop sizes in one workspace. Open ViewportStudio on an HTTP or HTTPS page to preview that site in up to 12 viewports. Choose device presets or custom dimensions, resize and arrange previews, and synchronize scrolling, supported clicks, eligible form inputs, and navigation. Reload previews, compare layouts side by side, or focus on one viewport. ViewportStudio needs access to HTTP and HTTPS sites to open the workspace on pages you choose. For sites that block embedding, the extension can adjust iframe response headers in the active workspace tab; you can turn this off. Previews share your browser's cookies and storage. Viewport sizes change CSS dimensions but do not emulate mobile hardware, and some sites may not work in embedded previews.