Free utility / no signup / browser-local
See your site at real-world CSS viewport sizes, then copy a testing matrix. Preview locally in your browser; cross-origin pages are not automatically inspected.
Enter a URL to build your mobile-to-desktop testing matrix.
Yes. Open the tool and use its free utility without signing in or entering a credit card. Launching a paid human-testing sprint is a separate, optional flow that requires an account and funding.
Enter a full HTTP or HTTPS website URL, or load the sample demo.
A sandboxed responsive preview and a copyable matrix from 360px mobile to 1920px desktop.
Some websites block embedding. Cross-origin pages cannot be automatically inspected; this tool does not certify that a layout passed QA.