A multinational toy company founded in New Zealand appears to have won a legal battle to force a review site to reveal the identities of aggrieved former workers who posted scathing reviews of its company culture.

Earlier this year Zuru, founded and run by the prominent Mowbray siblings, took legal action against Glassdoor, a US review site.

Users on Glassdoor post reviews of their experience working at companies.

Zuru's page featured a number of negative reviews and documents filed in a United States District Court in California show the toy giant wants Glassdoor to reveal the names and contact details of people who posted purported negative experiences.

In public statements, Zuru has described the negative reviews as "spam".

The company then intends to sue the users for defamation in New Zealand, court documents show.

Glassdoor earlier said it intended to fight to protect the identities of its users.

An order from United States Magistrate Judge Alex Tse released earlier this month shows the court has ruled in Zuru's favour.

The lengthy judgement from Tse said Glassdoor did not convince his court that the review site's interest in preserving the anonymity of its users outweighed Zuru's interest in protecting its reputation through defamation action in New Zealand.

"Because Glassdoor hasn't made that showing, and because Zuru's defamation claim is plausible, the Court will require Glassdoor to reveal who wrote the reviews," Tse's judgement said.

"Zuru's defamation claim, while plausible, almost surely won't make it off the ground without Glassdoor's help.

"Glassdoor knows who wrote the reviews, Zuru doesn't. And if Glassdoor doesn't identify the reviewers, Zuru can't sue them and will be left without a means by which to 'vindicate [its] good name.'"

The Herald is seeking comment from Glassdoor on whether it will appeal.

"Zuru's co-founders state that Zuru 'has had to expend money, time, and resources in combating the negative publicity, negative perception, and harm to [Zuru's] reputation that the reviews have caused.'

"As an example, the co-founders explain that after the reviews were published, they extended a job offer to a candidate for a management position, but the candidate declined the offer and cited the reviews as a reason for doing so."

Zuru was started by the Mowbrays in a Waikato Shed nearly two decades ago.

It is now among the world's biggest toy makers and is headquartered in Shenzhen, China.

Siblings Anna, Matt and Nick Mowbray remain directors, Companies Office records show.