If you want to know whether a page works well on phones and tablets, automated mobile‑friendliness testers are a quick way to find out. Tools such as the Mobile Friendliness Test that Microsoft has offered in its Bing Webmaster suite fetch and render pages, check a handful of common mobile issues, and give you a clear pass/fail verdict plus details on what to fix.
What these testers check
These tests aren’t mystery boxes — they try to mimic what a mobile browser sees and then flag things that make pages hard to use on small screens. Typical checks include:
- Viewport and scaling: is there a viewport meta tag so the page scales to the device width? Without it, pages often look tiny or require horizontal scrolling. - Layout and responsiveness: are elements sized and laid out so they adapt to narrow screens rather than requiring side‑scrolling or zooming? Tests look for fixed‑width containers and other layout constraints. - Readability: are font sizes large enough to read without zooming, and is line length reasonable? Tiny text is a frequent cause of failures. - Tap targets and navigation: are buttons and links big enough and spaced out so people don’t mis‑tap? Is the navigation usable on touchscreens? - Blocked resources and rendering: the tester’s crawler fetches CSS, JavaScript and images to render the page. If important resources are blocked by robots.txt, the crawler can’t render the page correctly. The tool will report any such blocked resources so you can decide whether to allow them. - Unsupported technology: use of deprecated or non‑mobile technologies can be flagged (for example, content that relies on plugins that mobile browsers don’t support).
The tool usually produces a rendered preview and aggregates these checks into a single mobile‑friendliness verdict, then offers details on specific failures so you can prioritise fixes.
How to act on the results
Run the test, then treat the report as a troubleshooting checklist rather than gospel. Steps to take include:
- Unblock resources the crawler needs. If CSS or JavaScript is blocked via robots.txt the tester can’t render the page correctly; allowing those resources to be crawled often clears up false failures. - Add or fix the viewport meta tag so pages scale sensibly on phones. - Use responsive design techniques: flexible grids, media queries and fluid images avoid the need for separate mobile pages and work across device sizes. - Increase base font sizes and improve spacing for lines and touch targets so reading and tapping are comfortable. - Remove or replace content that relies on unsupported plugins or that forces awkward interstitials on mobile users. - Re‑test after each set of changes. Automated tools are fast, but always verify fixes in real devices or device emulators to confirm the real‑world behaviour.
Automated mobile‑friendliness tools are a useful first step, but not the only step. Use them alongside manual testing on a few actual devices or emulators, and prioritise fixes for pages that matter most to your visitors and search traffic.