The head of the Christchurch Call says the global initiative has made it harder for people to weaponise the internet.
An 18 year old live-streamed himself shooting more than a dozen mostly-black people in a grocery store in Buffalo, New York, yesterday.
The attack was similar to the 2019 mosque terror attacks in Christchurch - involving a lone gunman, an assault-style rifle and a manifesto that referenced the 15 March attacks in New Zealand.
Paul Ash is the Prime Minister's special representative on cyber and digital and Christchurch Call co-ordinator at the Department of Prime Minister and Cabinet.
He told RNZ the Buffalo attack was not able to go "viral" because of new online tools introduced and supported through the Christchurch Call.
"The impact immediately after the Christchurch attacks was such that so many people globally saw the material turning up in their feeds or on their social media platforms.
"It was evident something had changed in the way terrorists and violent extremists were using the internet. We haven't seen anything like that [with the Buffalo shooting]."
Ash said this was in part due to the Global Internet Forum to Counter Terrorism (GIFCT) quickly activating its "content incident protocol" when the attack appeared online.
"What that means is the content from the attack is 'hashed'. So, signatures are taken from that material and are shared across the companies that run online platforms so that as items of content are identified they are able to be picked up when they're uploaded or when they're being shared and automatically taken down by the platforms."
Collaborative work between governments and companies had seen the GIFCT beefed up over the past few years to become an organisation that could immediately respond to a crisis, he said.
"It's gone from almost a virtual construct that ran a smaller version of the hash database to an organisation that is an independent not-for-profit that has its own staff based in three different locations who are able to work across a much wider range of companies."
Ash said he was confident the Christchurch Call was making a "significant difference" in the global effort against online extremism after the 15 March attacks.
"We have agencies here in New Zealand monitoring carefully for the content ... and we have not seen this material coming through our feeds the way it did with Christchurch. If we're looking at search engines, they seem to have done a very, very good job of managing the content.
"If we look at things like the manifesto, undoubtedly there are people trying to post some of that but they are seemingly being taken down almost as quickly as they are put up on the major platforms."
He said it was now much harder for people to weaponise the internet but noted the work in that area was "dynamic and a work in progress".
"As fast as new tools are built or new ways of identifying this kind of content are developed, the actors on the other side of the equation who would try to put this stuff onto the internet or abuse those platforms adapt and shift as well.
"So I don't know we're at the point of a steady state yet where it's not going to be possible for actors to carry out these acts and look to put content online but there have been really significant shifts."