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.

Responsive website testing tool guide

Build a repeatable responsive website testing workflow across phone, tablet, laptop, and desktop viewports.

Responsive design checker guide

Build a useful multi-screen check that finds layout and interaction failures instead of producing screenshots without conclusions.

Mobile view and device emulator

Understand viewport emulation, its limits, and how it complements Chrome DevTools and physical devices.

Chrome mobile view extension

Compare mobile, tablet, laptop, and desktop layouts from the page already open in Chrome.

Firefox mobile view testing

Separate Firefox Responsive Design Mode, Firefox for mobile, and real cross-browser testing.

Device viewport sizes

Choose representative CSS viewport widths and avoid confusing physical screen resolution with browser layout size.

Pre-release testing checklist

Cover layout integrity, touch and keyboard access, design comparison, evidence, and final physical-device checks.

A practical order for responsive testing

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

Free, private, and open source

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