Mobile View Toggle by Yasin Keleş

Mobile View Toggle lets you preview any web page exactly as it looks on a phone or tablet — without leaving Firefox.

Click the toolbar button (or press Alt+Shift+M) to open the current tab in a dedicated mobile-sized window. The window uses a real mobile User-Agent and modern Client Hints, so responsive sites render their true mobile layout. Each tab can be toggled independently, and you can keep several mobile previews open at the same time.

Inside the mobile window a slim control bar lets you:

Switch device — iPhone, Android (Pixel), or iPad
Rotate between portrait and landscape
Capture a screenshot — instantly copied to your clipboard, with an optional Download button

Keyboard shortcuts:

Alt+Shift+M — toggle mobile view
Alt+Shift+S — capture the mobile window

Privacy:

No data collection
No account required
No tracking or analytics

Perfect for web developers, designers, QA testers, and anyone who wants to quickly check how a site behaves on mobile.