Google began its efforts to maneuver websites over to mobile-first indexing over six and a half years in the past. At present, Google confirmed these efforts are actually completed, and the final batch of web sites eligible for mobile-first indexing have been moved over.
Affirmation. John Mueller from Google confirmed immediately was the final batch on Mastodon immediately after I reported there was a large batch of web sites moved to mobile-first indexing up to now a number of hours. John stated that this was the “final batch!”
Not all websites moved. John added that there’ll nonetheless be a “tiny handful of web sites that actually don’t work on cell are left.” These remaining websites, he stated, will “simply be crawled with desktop Googlebot going ahead.”

Notifications. At present, various SEOs observed that websites which were on desktop-first indexing had been notified they had been moved to mobile-first indexing. Here’s a screenshot from Richard Hearne he posted on Twitter:

Historical past. As a reminder, Google began mobile-first indexing over 6.5 years in the past, and ultimately, after publishing deadline after deadline, Google eliminated the deadline. Google first launched mobile-first indexing again in November 2016, and by December 2018, half of all websites in Google’s search outcomes had been from mobile-first indexing. Cell-first indexing merely signifies that Google will crawl your web site from the eyes of a cell browser and use that cell model for indexing and rating.
Google in early March 2020, earlier than all of the lockdowns started throughout a lot of the world, introduced the deadline for all websites to change over to mobile-first indexing could be September 2020. At the moment, Google stated, “To simplify, we’ll be switching to mobile-first indexing for all web sites beginning September 2020.” Then in July 2020, Google moved that deadline as soon as once more to March 2021.
Why we care. So in case your web site has not but been moved to mobile-first indexing, then it’d by no means transfer to mobile-first indexing. Oh, all new websites by default, must be listed over mobile-first indexing. The difficulty is, John stated, websites that weren’t moved over “don’t work with cell user-agents in any respect.”
This took quite a bit longer than anybody anticipated, however the course of appears to be formally now completed.