Mobile Viewport Checker
Check the viewport declaration and the mobile problems visible in the HTML.
About this tool
Checks the viewport meta tag and the other mobile problems that can be seen in the markup: zoom disabled, fixed pixel widths declared inline, tiny font sizes, and Flash or other plugin content.
What it will not do is give you a verdict on whether the page is usable on a phone. Tap target spacing and content overflow depend on CSS that is not loaded here, and any tool claiming otherwise from a single HTML fetch is guessing. The viewport tag is worth checking on its own — it is the most common single cause of a page rendering as a shrunken desktop layout.
Common questions
What should the viewport tag be?
width=device-width, initial-scale=1 covers almost every case. With neither, a phone assumes a 980-pixel desktop layout and scales the page down, which is why text appears tiny. initial-scale=1 on its own does set the layout width in current browsers, so a page with only that is not broken.
Why should I not disable zoom?
user-scalable=no and maximum-scale=1 stop people enlarging text. For anyone with low vision that can make a page unusable, and it is a WCAG failure. Modern iOS ignores it, which tells you what the platform thinks of it.
Does this replace Google's mobile test?
No. This reads the HTML; a real verdict needs the page rendered with its CSS and JavaScript. Use this to catch the obvious declaration mistakes, then look at the page on an actual phone.
Is mobile-friendliness a ranking factor?
Yes, and more fundamentally Google indexes the mobile version of your site rather than the desktop one. If content is missing on mobile, it is missing from the index.