Mobile Friendly Viewport Tester — mobile friendly

Mobile Friendly Viewport Tester is a lightweight Firefox extension created for developers, UI designers, and SEO professionals who need to quickly evaluate mobile viewport behavior on modern websites. The extension helps identify responsive layout issues and viewport inconsistencies directly inside the browser without requiring external testing platforms.

Modern search engines prioritize mobile usability and responsive performance. This tool allows users to instantly inspect viewport settings, screen adaptation behavior, and mobile rendering compatibility while browsing webpages. It simplifies responsive testing workflows and helps improve mobile optimization for better usability and search visibility.