Mobile Friendly Checker
Test your HTML source code for mobile-friendliness signals. Check viewport configuration, responsive design, touch targets, font sizes, and image handling -- the factors that drive mobile-first indexing.
- 8 mobile usability checks covering viewport, responsive CSS, and touch targets
- Score out of 100 with specific fix recommendations for every issue
- Runs entirely in your browser -- your source code never leaves your device
How to Test Mobile Friendliness
Check your page for mobile usability issues in four simple steps.
Copy Your HTML Source
View the page source of your website (right-click, View Page Source) and copy the entire HTML content.
Paste HTML Here
Paste the full HTML source code into the text area. The tool analyzes the raw markup for mobile-friendliness signals.
Review Mobile Checks
The tool evaluates 8 mobile-friendliness criteria including viewport, responsive CSS, touch targets, and font sizes.
Fix Issues
Follow the specific recommendations for each failing check to improve your mobile experience and SEO performance.
Copy Your HTML Source
View the page source of your website (right-click, View Page Source) and copy the entire HTML content.
Paste HTML Here
Paste the full HTML source code into the text area. The tool analyzes the raw markup for mobile-friendliness signals.
Review Mobile Checks
The tool evaluates 8 mobile-friendliness criteria including viewport, responsive CSS, touch targets, and font sizes.
Fix Issues
Follow the specific recommendations for each failing check to improve your mobile experience and SEO performance.
Mobile-First Indexing and Why Mobile Friendliness Drives SEO
Mobile-first indexing is no longer a preview or a gradual rollout -- it is the default for every website on the internet. Since March 2021, Google has used the mobile version of your site as the primary version for crawling, indexing, and ranking. If your site does not render well on mobile devices, Google is effectively seeing a broken or suboptimal version of your content, and your rankings will reflect that.
The shift to mobile-first was driven by user behavior. Over 60% of global web traffic now comes from mobile devices, and in many markets that number exceeds 75%. Google simply aligned its indexing strategy with how people actually browse the web. The practical implication is clear: if your site is not mobile-friendly, you are not just providing a poor experience to the majority of your visitors -- you are actively undermining your ability to rank in search.
The Viewport Meta Tag Is Non-Negotiable
The viewport meta tag is the single most important element for mobile rendering. Without it, mobile browsers default to rendering your page at a desktop width (typically 980 pixels) and then shrinking the entire page to fit the screen. The result is text that is unreadably small, links that are impossible to tap, and a user experience that guarantees an immediate bounce. The correct viewport tag tells the browser to match the page width to the device screen: <meta name="viewport" content="width=device-width, initial-scale=1">.
This tag should be present in the <head> section of every page on your site. It is not enough to add it to your homepage -- Google crawls and indexes individual pages, and each page needs its own properly configured viewport tag. If you use a templating system or framework, ensure the tag is included in your base layout so it propagates to every page automatically.
Responsive Design vs. Separate Mobile Sites
Google recommends responsive web design as the best approach for mobile optimization. Responsive design uses CSS media queries to adapt the layout and styling based on the screen size, serving the same HTML to all devices. This approach has several advantages: there is a single URL for each piece of content (no duplicate content issues), all backlinks point to the same URL (no link equity dilution), and maintenance is simpler because there is only one codebase.
The alternative approaches -- separate mobile URLs (m.example.com) and dynamic serving (same URL, different HTML) -- are still supported by Google but add significant complexity. Separate mobile sites require canonical and alternate annotations to avoid duplicate content penalties. Dynamic serving requires the Vary HTTP header to ensure caches serve the correct version. For most websites, responsive design is the superior choice from both an SEO and maintenance perspective.
Touch Targets and Mobile Usability
One of the most common mobile usability issues flagged in Google Search Console is touch targets that are too small or too close together. The recommended minimum size is 48x48 CSS pixels with at least 8 pixels of spacing between adjacent targets. This standard is based on ergonomic research -- the average adult fingertip covers an area of about 10mm, which translates to roughly 48 pixels at standard screen density. When touch targets are smaller than this, users frequently tap the wrong element, leading to frustration and higher bounce rates.
Common offenders include navigation links in dense menus, footer link lists, and small icon buttons without adequate padding. The fix is straightforward: increase the padding around interactive elements rather than necessarily making the visible element larger. A link can have 12px of visible text but 48px of tappable area if it has sufficient padding. This approach preserves your visual design while meeting the technical SEO requirements for mobile usability.
Font Sizes, Content Width, and Image Handling
Google flags font sizes below 12px as a mobile usability issue, but best practice is to use at least 16px for body text. At 16px, text is readable without pinch-zooming on most devices, and it provides a comfortable reading experience that keeps users engaged. Pair readable font sizes with a line-height of at least 1.5 for body text to ensure lines of text do not feel cramped on small screens.
Content that extends beyond the viewport width forces horizontal scrolling, which is one of the most disruptive mobile UX problems. This typically happens when elements have fixed pixel widths that exceed the screen width. Use percentage-based widths, max-width constraints, and the CSS overflow property to ensure content adapts to any screen size. Images are a common culprit -- always apply max-width: 100% and height: auto to images, and use the srcset attribute for resolution-appropriate image delivery.
For a comprehensive assessment of your mobile performance including Core Web Vitals, rendering behavior, and mobile-specific SEO audit findings, our team provides detailed reports with prioritized fix recommendations tailored to your specific technology stack.
Frequently Asked Questions
Common questions about mobile friendliness, responsive design, and mobile SEO.
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