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mobile-seo-checker

A mobile SEO checker audits a page for the signals Google uses in its mobile-first index — the index used to rank every site since 2023. The ZTools Mobile SEO Checker covers viewport meta tag, minimum font sizes (16 px body recommended), tap-target spacing (48×48 px minimum per WCAG and Google's mobile-friendly rules), image responsiveness (srcset / <picture> usage), text-to-tap-target ratio, mobile speed signals (LCP, CLS), and content parity (mobile content matches desktop). Each issue is reported with the affected element so fixes are immediate.

Use cases​

Pre-launch mobile readiness check​

Before announcing a new site, run the mobile checker. Catches the easy mistakes — missing viewport meta, 12 px body text, tap targets too close — before mobile users (and Google's mobile crawler) experience them.

Diagnosing a sudden mobile-rankings drop​

A page that ranked well on mobile suddenly doesn't? Often a recent CSS change broke the mobile layout (text too small, buttons too close). The checker surfaces the regression.

Auditing tap-target accessibility (WCAG 2.5.5)​

WCAG AAA requires 44×44 px touch targets. The checker maps every interactive element's actual size on a 375 px viewport and flags violations.

Verifying mobile/desktop content parity​

Some sites hide content on mobile via display: none — Google's mobile-first index then misses that content for ranking. The checker compares mobile and desktop content trees.

How it works​

  1. Enter a URL — Public HTTP/HTTPS URL. The tool fetches the page and renders it at a 375×812 mobile viewport (iPhone X size).
  2. Check viewport meta tag — Missing viewport meta is the #1 mobile SEO killer. Tool flags absence and recommends <meta name="viewport" content="width=device-width, initial-scale=1">.
  3. Audit text sizes — Every text element measured at the rendered mobile viewport. Body text below 14 px flagged; below 12 px flagged as critical (Google's mobile-friendly rule).
  4. Audit tap-target sizes and spacing — Every link, button, and input rendered. Targets under 44×44 px or with neighbors closer than 8 px flagged.
  5. Mobile speed signals — LCP, CLS, FID/INP estimated from the page load on a throttled mobile connection. Detailed perf audit in our Page Speed Analyzer.

Examples​

Input: https://example.com (viewport meta present, body 16px, tap targets ≥48px)

Output: PASS. Viewport ✓. Font sizes ✓. Tap targets ✓. LCP 2.1s ✓.

Input: https://example.com/legacy (no viewport, 12px body, links 24px tall)

Output: CRITICAL: viewport meta missing. ERROR: body text 12px (rec 16px). ERROR: 8 links under 44px.

Frequently asked questions​

Is mobile SEO different from regular SEO?

Since 2023, Google indexes the mobile version of pages first. So "mobile SEO" IS regular SEO; the desktop-only mistakes (popups that block mobile, tiny text, slow mobile load) directly hurt rankings.

What's the minimum body font size for mobile?

Google's mobile-friendly rule: 12 px minimum, 16 px recommended. Below 16 px on mobile is uncomfortable for most readers; below 12 px Google flags as mobile-unfriendly.

What's the minimum tap-target size?

Google: 48×48 dp. WCAG AAA: 44×44 px. Apple HIG: 44×44 pt. The checker uses 48 px as the practical minimum and 44 px as the absolute floor.

Should mobile content match desktop?

Yes for Google's mobile-first index — content shown only on desktop is essentially invisible to Google. If you must collapse content on mobile, use accordions or "show more" toggles (still in DOM) rather than display: none.

Will the checker handle SPAs?

It analyzes the initial HTML response. For JS-rendered SPAs, the bot view is what matters for SEO — the checker correctly shows that view.

What about the AMP format — is it still relevant?

No — Google deprecated AMP's SERP boost in 2021. Modern responsive HTML with good Core Web Vitals is the recommended path. Don't invest in new AMP work.

Tips​

  • Always set the viewport meta — single biggest mobile-SEO fix for legacy sites.
  • Default body text to 16 px on mobile; nothing under 14 px without a strong reason.
  • Tap targets minimum 48×48 px with at least 8 px gap from neighbors.
  • Avoid mobile popups that block content — Google penalizes intrusive interstitials.

Try it now​

The full mobile-seo-checker runs in your browser at https://ztools.zaions.com/mobile-seo-checker — no signup, no upload, no data leaves your device.

Open the tool ↗

Last updated: 2026-05-05 · Author: Ahsan Mahmood · Edit this page on GitHub