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RankBrain

Mobile-Friendly Test

Checks mobile-related HTML and, when available, a phone-sized browser sample; not every visitor’s experience.

We load the page for you. Our server fetches the public address you enter and reads the response. Nothing you enter is stored. One step loads the page in a real browser on our side. Free, no account.

Finding the problem is the first half.

RankBrain fixes the viewport tag, fixed widths and tap targets in your templates.

RankBrain works on websites built in code, through the AI tool you already use (Cursor, Claude Code, Codex, ChatGPT).

Check my site free

How it works

You open your site on a phone and something is off: text you have to pinch to read, a button that will not tap. When browser capacity allows, this test samples Chrome at 390 × 844 for text size, tap targets and overflow, with a first-screen screenshot. Otherwise it reports HTML and CSS checks, not rendered measurements.

  1. 1

    The page is loaded in Chrome at 390 × 844, the size of a current phone. We measure whether content is wider than the screen, how much of the text is 12 px or larger, and which tap targets are small and crowded.

  2. 2

    You get a screenshot of the first screen, so you can see what we saw.

  3. 3

    Our server separately reads the HTML and CSS sent to a phone: the viewport tag, zoom blocking, breakpoints, fixed widths, responsive images and page weight.

What it does not do

  • Google retired its own Mobile-Friendly Test in December 2023. This test uses its own disclosed checks; it is not Google's verdict.

  • The real-browser run has a daily capacity. When it is used up, the HTML and CSS checks still run and the page says so.

When a source is busy or a site does not answer, this tool says so. It never fills the gap with a guess.

Questions

Google retired its Mobile-Friendly Test. Is this the same thing?

No. This test uses its own disclosed checks, but it is not Google's verdict. The page is loaded in Chrome at 390 × 844 on our side, and we measure content wider than the screen, how much of the text is 12 px or larger, and which tap targets are small and crowded. The server also reads the viewport tag, zoom blocking, breakpoints, fixed widths and page weight.

Why does my page look fine on my phone but fail the test?

The test uses a 390 × 844 viewport in Chrome, which is one current phone size. Your phone may be wider, and a page can look fine there while a narrower screen overflows. Check the screenshot and the list of content wider than the screen. Fixed widths, a missing viewport tag or a blocked zoom usually explain it, and the HTML and CSS checks name them.

What happens when the browser capacity is used up?

The real-browser run has a daily capacity. When it is used up, the HTML and CSS checks still run and the page says the browser part is missing. You still get the viewport tag, zoom blocking, breakpoints, fixed widths, responsive images and page weight, read from the HTML and CSS. Come back another day for the screenshot and the rendered measurements.

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