I'm currently developing a mobile version of my site where users' devices are automatically identified and then displayed either mobile or desktop view of the same URL.

For usability purposes, I would like to display different information on certain URLs in mobile than desktop. For example, I'd prefer the content to be straight on first page on mobile, whereas my desktop root domain is a landing page.

  • How will such arrangement affect Google's opinions about my site?
  • Is is hurtful for my rankings?
  • Or does Google separate desktop and mobile results?

It appears that you're worried that serving different content to mobile users than to desktop users at the same URL, using user-agent detection, might be considered a form of cloaking, and thus penalized by Google.

According to the Google Webmaster Central Blog, this is not the case, provided that you do the mobile browser detection properly. Essentially, the important detail to realize is that Google's crawlers use different user-agent strings depending on whether they expect desktop or mobile content. For example, a typical user-agent string for normal Googlebot requests would be:

Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)

whereas for requests from the mobile crawler, you'll see something like:

SAMSUNG-SGH-E250/1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1
UP.Browser/ (GUI) MMP/2.0 (compatible; Googlebot-Mobile/2.1;

or (for smartphone requests):

Mozilla/5.0 (iPhone; CPU iPhone OS 6_0 like Mac OS X) AppleWebKit/536.26
(KHTML, like Gecko) Version/6.0 Mobile/10A5376e Safari/8536.25 (compatible;
Googlebot/2.1; +http://www.google.com/bot.html)

As long as you make sure that you correctly detect the latter type of Googlebot requests (and not the former type) as mobile, and serve mobile content to them, everything should be fine. Basically, the important thing is that normal Googlebot requests need to receive desktop content, while mobile Googlebot requests need to receive mobile content.

Here's a nice diagram illustrating this, from the Google Webmaster Central Blog article I linked to above:


Also, to let Google's crawler know that there might be different content available for mobile browsers, you'll want to configure your web server to send the Vary: User-Agent HTTP header for any pages that you're using user-agent detection for. You'll also want to make sure to avoid common pitfalls when detecting user-agents.


The best course of action is to use canonical URLs. This avoids a situation where you are penalized for duplicate content.

When it comes to desktop vs mobile websites, most sites will have something like this on their mobile website:

Example for: http://m.mywebsite.com/page.html

<link rel="canonical" href="http://mywebsite.com/page.html" />

The canonical tag basically tells Google that the same content can be accessed via multiple URLs.

Desktop / Mobile users are detected by the server and redirected to the appropriate version (this happens on Blogger, which is owned by Google).

With this method, Google will not separate the results (you do not want this). It also means that inbound links to mobile pages will give weight / "link juice" back to the original page. In this case, links to http://m.mywebsite.com/page.html will affect http://mywebsite.com/page.html


In my experience, mobile visitors want the same content as your desktop visitors do. I worked for a travel website with lots of information about hotels and restaurants. The site is generally known for hotels, but we thought that mobile users would be much more interested in restaurant content because they we looking for something when they were out. That assumption was not correct, mobile users were looking for the hotel content just as much as the desktop users.

I've also heard the argument that paring down content can help the mobile experience because pages load faster. I've found that it is rarely content that causes pages to load slowly on mobile.

  • Latency is a bigger issue than download speed on mobile. Large pages are not the problem, but each request can take seconds to make. It often makes sense to put more content on the page and let the user scroll to it rather than making them click to more pages.
  • The weight of the content is often dwarfed by the weight of the markup, CSS, and JavaScript. Start with the things the user can't see when trying to remove bytes from the page.

Users tend to get frustrated when they can't use the mobile site the way that they use the desktop site. Google uses user satisfaction as a major signal in their ranking algorithms. I doubt that Google would penalize your site outright for serving different content to mobile users. However, when users find your site to be less usable than they were hoping, your rankings will fall.

  • 1
    "Users tend to get frustrated when they can't use the mobile site the way that they use the desktop site" totally agree – krokola Jun 24 '14 at 12:31
  • @Stephen what you mean by Latency? What is the cause of it? – AgA Jun 27 '14 at 6:01
  • Latency is round trip time. The time that it takes the user to initiate an action until it gets an acknowledgment of that action from the server. Latency is pretty normal when the phone has wifi, but is much higher when connected to the internet via cell tower. – Stephen Ostermiller Jun 27 '14 at 9:25

You can display a mobile version using canonical and rel alternate tags , desktop version showing the alternate tag and mobile version showing the canonical tag. When serving dynamic HTML on the same URL you should use the vary HTTP header.

Google explains this in detail:



Google is smart enough to detect mobile vs. non-mobile sites. And comments specifically that this is not viewed as spam.

The more important consideration is to mark your preferred URL as canonical.

From Google's WMT:

Duplicate content generally refers to substantive blocks of content within or across domains that either completely match other content or are appreciably similar. Mostly, this is not deceptive in origin. Examples of non-malicious duplicate content could include:

Discussion forums that can generate both regular and stripped-down pages targeted at mobile devices
Store items shown or linked via multiple distinct URLs
Printer-only versions of web pages

This has been well documented since 2010.

See the SEL article on:

Don’t Penalize Yourself: Mobile Sites Are Not Duplicate Content

More recently, Google's Matt Cut's has said not to worry too much about duplicate content. The issue is more of which page you want to rank in the SERPs.

How does required duplicate content (terms and conditions, etc.)

Lastly check out google's webmaster tools topic on:

Duplicate Content

Also SEOMOz, has a great article on the topic:

What is Duplicate Content


Google's words: When a website is configured to serve desktop and mobile browsers using different URLs, webmasters may want to automatically redirect users to the URL that best serves them. If your website uses automatic redirection, be sure to treat all Googlebots just like any other user-agent and redirect them appropriately.

Google recognizes three different configurations for building mobile sites.

Google does not favor any particular URL format as long as the page(s) and all page assets are accessible to all Googlebot user-agents.

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