Tuesday, May 28, 2019
Over the years since announcing mobile-first indexing—Google's crawling of the web using a smartphone Googlebot—our analysis has shown that new websites are generally ready for this method of crawling. Accordingly, we're happy to announce that mobile-first indexing will be enabled by default for all new, previously unknown to Google Search, websites starting July 1, 2019. It's fantastic to see that new websites are now generally showing users—and search engines—the same content on both mobile and desktop devices!
You can continue to check for mobile-first indexing of your website by using the URL Inspection Tool in Search Console. By looking at a URL on your website there, you'll quickly see how it was last crawled and indexed. For older websites, we'll continue monitoring and evaluating pages for their readiness for mobile first indexing, and will notify them through Search Console once they're seen as being ready. Since the default state for new websites will be mobile-first indexing, there's no need to send a notification.

Our guidance on making all websites work well for mobile-first indexing continues to be relevant, for new and existing