Facebook is now more important than Google for online publishers

Facebook is starting to drive more traffic to digital media websites than Google is, according to new data from Parsely, an analytics firm which collects data for about 400 digital publishers, including Conde Nast, Reuters, Mashable, and The Atlantic.

Facebook's rise has been slow and steady since at least 2012, as it has been gradually wining referral traffic marketshare from Google Sites, which includes properties like Google News and Google.com web search.

Instead of SEO experts popping up everywhere, now it's social media optimizers.

A shift like this lends some credence to the theory that the world's biggest publishers saw a dramatic drop in web traffic in April because of a Facebook algorithm tweak rolled out around the same time. (A Facebook spokesperson told Business Insider that it didn't see an overall decline in aggregated referral traffic in April.)

Here's the main chart showing the traffic referral trend:

And here's where Parsley's network gets most of its referral traffic overall:

This shift comes even as Facebook reveals ambitions to get more of that content on its own site.

Facebook launched its much discussed publishing product - Instant Articles - earlier this summer to let media companies post their articles directly to its iOS app. Although multiple reports have pointed to an upcoming onslaught of more Instant Articles from publishers like The New York Times and The Atlantic, those floodgates haven't opened quite yet.

Happily for Facebook, not all of the new traffic it's funneling to digital sites comes for free.

BuzzFeed, for example, spent millions of dollasr last year to promote its clients' ads, according to internal financial documents published by Gawker, and many other digital publications will occasionally pay to boost well-performing posts.