Google’s John Mueller gave a presentation at Search Marketing Expo (SMX) Munich earlier this week and has revealed some interesting new details about Mobile-First Indexing.

For us SEO’s, we have some important new details that we can use to track when Google begins the transition for sites that we manage. 

One of the new pieces of information was that site owners will receive a notification through Google Search Console (GSC) when indexing has changed to Mobile, along with an annotation within reports which I imagine will look something like this:

Google Search Update

While this information is extremely useful, an idea has been provided by John (very unusual for Google to give away this sort of information) for how you can track the transfer yourself.

It involves using the adding the following code to your website. This is in PHP, but you can adjust for whatever server-side language your website/CMS is written in: 

<! -- User-agent: <?php echo $_SERVER[“HTTP_USER_AGENT”]; ?> -->

The idea is that you can log the user agent, basically the fingerprint of the computer accessing your website, in the HTML source code of your website.

Then you can check Google’s cached page source code, cleverly showing you which Googlebot, desktop or mobile, hit your website!

What comes next?

Apparently a considerable amount of sites have already made the transfer over to Mobile-First Indexing, although there haven’t been any reports of SEO’s getting the notification through GSC just yet.

I image that we will start to receive these soon though, and it will be an inbox explosion like we saw when the new Google Search Console Beta interface rolled out:

Google Search Console Notifications

Although instead of waiting for Google to decide when to tell you about the change, it’s worthwhile implementing this process to see first-hand for yourself.

We hope you found this guide useful, and we’ll keep you posted when our magic code has come into play – hopefully we can find out before Google tells us!