Responsive testing library

Test the right screens for the right reasons.

Responsive testing is more than opening a phone-sized frame. These guides explain which viewports to choose, what a browser simulation can prove, how to compare several layouts efficiently, and when to move to physical hardware.

A practical order for responsive testing

  1. Start with a compact phone, large phone, tablet, and laptop viewport.
  2. Exercise the same navigation and content state across those widths.
  3. Check immediately around real CSS breakpoints with custom viewports.
  4. Capture the failure with the viewport, expected result, and actual result.
  5. Verify critical journeys in target browsers and on physical devices.
Free, private, and open source

Mobile View & Responsive Tester runs locally as a Chrome extension. There is no account, subscription, extension telemetry, or remote application backend.