As much as online advertising has enjoyed enormous success in recent times, the majority of this growth has been within the confines of Google and Facebook’s ‘walled gardens’.

Advertising trade group Digital Content Next recently estimated the two tech giants account for 90 per cent of the ad industry’s annual growth.

But today it seems as though there are some ‘cracks’ beginning to appear in these walled gardens.

This is in part being driven by the seemingly imminent death of third-party cookies in online advertising and growing privacy concerns among the public.

But the change is opening the door for some non-Google and Facebook adtech providers.

“Without the independent open web – as we would call that area outside of those walled gardens – thriving, I guess the big players can do what they want, which doesn’t help anybody apart from big players of course,” said Rubicon Project ANZ country manager Rohan Creasey during a panel discussion in Sydney last week.

Online consortium prebid.org has been established to give smaller players the platform to compete with the duopoly by setting the standard for header bidding.

It is a response to the waterfalling method that ultimately allowed Google to establish much of its dominance.

“The march forward of Prebid is pretty inevitable at this point because we want a community asset and you want the ability to switch from one vendor to another with very little dislocation,” said Rubicon Project CTO and Prebid board member Tom Kershaw.

“It does give you that. You can literally go in and dump a partner and add a partner in 10 seconds if you want now.”

This is a stark contrast to migrating from a provider like Google Ad Manager (GAM), which can quickly become a major project for a business.

Opensourced, Prebid.org has already had 433 different engineers contribute to the code base this year, theoretically now giving it the scale to compete with the much larger competitors.

What does life outside the walled gardens look like?

So is an initiative such as Prebid capable of single-handedly usurping Google? Probably not.

But there is no doubt that the tide is turning on the search engine’s market dominance.

News Corp GM commercial operations Jason Denny expects a changing political climate to impact Google’s operations.

“I think that the cracks will happen due to legislation,” he said.

“You see what’s going on in the US right now with these presidential elections nearing. Elizabeth Warren talking about breaking up the Google’s and Facebook’s of the world.

“I think that that’s how those fissures are going to come about.”

REA automation & audience commercial product director Amy Jansen said: “You need legislation to enforce change because at the moment there’s nothing to prevent that any competitive behaviour.

“The key benefit on the back of the ACCC report for independent ad tech is the possibility that new legislation will force the likes of Google, Facebook and Amazon to be less anti-competitive in the way that they monetise their supply.”