It was hailed as an unprecedented response to an unspeakable act of terror.
But one year on from the attack that left 51 people dead, has the Christchurch Call to Action made any difference, or is it what National leader Simon Bridges calls "a big talkfest ... that has achieved nothing"?
People across the tech industry and government said the Call has made a positive difference that New Zealand - often left off many world maps - should be proud of.
"It has had a direct impact in nudging [tech] companies to do better," said Jordan Carter, chief executive of InternetNZ, which is a member of the Call's advisory network.
"The process of doing it has raised New Zealand's profile in global Internet policy debates. As a country we have a responsibility to use that for good."
• Christchurch Call to Action: Govts, tech companies agree to tackle violent online content on social media
• Christchurch Call update: Social media giants join forces to fight extremism
• Premium - Derek Cheng: Paris summit to seal Christchurch call to action exceeds expectations
• Christchurch Call counters copycat shooting in Germany - PM
The Islamic Women's Council of NZ, which is also a member of the network, said the Call has brought together an impressive number of countries, companies and industry stakeholders, and the biggest difference was how quickly online platforms moved to take down horrific content.
The Call was a response, driven by Prime Minister Jacinda Ardern, to how online media platforms were weaponised in the March 15 terror attack, when there were 1.5 million attempted uploads of the video footage in the first 24 hours.
It was so widespread, even Ardern inadvertently saw the footage.
The summit in Paris two months after the attack was seen as the first time governments, tech companies and civil society all agreed on collaboration to combat online terrorism and violent extremism.
By September, when membership had expanded to 53 countries and organisations, as well as all the major tech companies, an online civil defence-type framework was launched to stop horrific content from going viral.
The Global Internet Forum to Counter Terrorism (GIFCT) - an organisation of all the major tech companies - would also be restructured as an independent NGO with its own protocol to help online media platforms work together to remove such content.
It was almost immediately put to the test in the terrorist attack in Halle, Germany, in October, which was livestreamed on Amazon's Twitch and viewed about 2200 times.
It took about five hours between the earliest communication among GIFCT members until GIFCT's protocol was officially launched - by which time Twitch had removed the original content.
Halle showed that the tech companies had come a long way in improving their response, according to Paul Ash, the senior official at the Department of Prime Minister and Cabinet who has been leading much of the Government's work on the Call.
"The key is to measure what would have happened prior to March 15 and what happened in October - and the difference was huge," Ash said.
On March 15, Ardern has said there were a series of unsatisfactory phone calls from the Beehive to tech companies, which exposed the lack of a tested, co-ordinated response.
Asked for her reflections one year on, Ardern said: "We already know it's made a difference.
"When we've seen devastating attacks [in Germany], coordination has kicked in straight away and helped prevent the viral spread of horrific and hateful videos. That didn't exist when we experienced March 15, but it does now."
Ash said while much had changed, there was "a long way to go".
In hindsight communication about Halle could have been more rapid, but Ash said that would improve when the new structure of the GIFCT was properly established, including its own independent advisory committee and an executive director.
That position is still yet to be appointed, despite being announced in September.
Part of the next phase of work is prevention, including research on the tech companies' own algorithms and their unintended consequences of pulling users towards more extreme content.
But companies have been reluctant to share them because doing so might jeopardise their intellectual property.
Carter said the work on algorithms has had the least progress so far.
"I don't expect the companies to give everyone access to their algorithms, but building a proper research framework should help them better understand what these tools are doing, and can give more information to researchers - or anyone interested in overseeing or understanding what these firms are doing."
Ash was confident that work would take place, due in part to the level of trust built up over the last year.
"The fact that we can have very open, transparent conversations with industry and with civil society is a big step forward.
"My sense is we have moved from a place where the real concern was around IP, to how we make sure the outcomes of those processes don't cause harm."
Ardern has built much of that trust herself from face-to face meetings and one-on-one phone calls with tech company executives including Facebook's Sheryl Sandberg, Microsoft's Brad Smith, and Twitter's Jack Dorsey.
It was also Ardern who contacted heads of state including Germany's Angela Merkel and France's Emmanuel Macron to develop the idea of the Christchurch Call.
Scrutiny from the Call has also been a catalyst for tech companies to do more.
Facebook has restricted live streaming, put interventions in place to steer people away from far-right content, and is building AI capacity using real-life shooting footage supplied by the UK and US governments.
YouTube also put tighter restrictions on livestreaming, while Twitter banned political advertising and has just announced work with researchers at Otago University to promote tolerance online.
Ardern said the latest work was due to "a connection we helped to make directly with Twitter last year".
But Islamic Women's Council spokeswoman Anjum Rahman said the platforms needed to do more.
"Ultimately it doesn't adequately address online hate. I don't think they've seriously addressed that, or where people are using hate to gain political support.
"For example, you have leaders of countries that are constantly violating the rules of Twitter, but are not removed, whereas you and me saying similar things would be removed."
She was also concerned about the GIFCT's independent advisory committee, and feared it would not adequately represent groups that are often the targets of hate.
That concern was shared by Ash, who said the Government wanted to ensure the committee included minority groups, different countries - not just Western ones - researchers and advocates of human rights and free speech.
The members of the Call owed it to the victims of March 15 to continue to pressure tech companies, he said.
"The people that perpetrate this sort of evil act have not gone away. They're still there and they're going to keep doing it, and they will keep looking to evolve their methodologies.
"Nothing that we do here will take away the devastation and the horror of what happened, but New Zealanders can be proud of the work that's being delivered here. I think it's made a big difference. It's one of the legacies of March 15."
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Whats Up?: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
If it is an emergency and you feel like you or someone else is at risk, call 111.