Alyssa Hardy doesn't enjoy leaving a negative review online. "But when they're deserved," she told the ABC, "I do."

On Wednesday, the Sydney-based emergency health worker made the decision to leave a negative review of the real estate agency Wills Property. Not because she was a former client, but because of what she had seen on TikTok and Facebook.

A rental listing for a three-bedroom apartment managed by Wills Property went viral on social media earlier this week due to its unusual conditions.

Those conditions included tenants being required to help maintain the childcare centre below, as well as being unable to leave or enter the apartment in the 10 hours the centre was open.  

Those posts on TikTok, Reddit and Facebook resulted in the listing being removed. But it also elicited a sense of outrage in some, including Ms Hardy.

"Another person had given them a Google review, and I wanted to do the same to let the public know what was happening, in a way that was a bit more public than a private Facebook group," Ms Hardy told the ABC.

The rise of digital vigilantism

A phenomena that's emerged in the wake of the internet is digital vigilantism. 

One example of this is when users will intentionally negatively review a business online as a form of retribution for its behaviour.

In some cases, large numbers of accounts, or a few people using multiple accounts, will organise to mass-negatively review a business to damage its reputation, an act known as review bombing.

Ms Hardy's review, which has now been removed by someone other than her, was intended to raise public awareness of the listing. But two hours after she posted, the 26-year-old received a reply from Wills Property.

That reply acknowledged that she was not a former client and referenced lawyers. But it also listed Ms Hardy's employer.

"I think they were trying to intimidate me," Ms Hardy said, adding that she was also contacted by Wills Property on her personal Instagram.

'Felt very, very violating'

Since the first days of the internet, people have shared information about themselves and others online. But as life becomes more centred around digital platforms, the potential repercussions of this communication has magnified. 

One aspect is how far and fast ideas can spread online. 

In 2020, a trend on TikTok eventually led to K-Pop fans organising online to collectively undermine a political rally for then-US president Donald Trump.

But another is how our information can be used. Doxxing, for example, is one phenomenon where private information is intentionally shared online to cause harm.

As with Ms Hardy, Wills Property found personal information elsewhere online of those who posted about its listing, including replying to a second negative review — which is also now removed — noting their town of residence and ABN number.

The agency also contacted the user behind a thread on Reddit about the listing, emailing them via their personal and work addresses while also messaging their partner on LinkedIn and Instagram.

"They reached out to my partner, which I just thought was just going too far, and it just felt very, very violating," said Reddit user Cords9836, a 25-year-old from Sydney's inner west.

"I haven't heard anything else, but I was definitely nervous, especially when they reached out to my work email address. That just felt a bit predatory."

In a statement to the ABC, Wills Property director John Wills said individuals in the business had received "personal threats" since the listing was posted on social media, and that they only posted "publicly available information".

"Since this story broke, Wills Property has been flooded with calls and correspondence to our office. These communications to us have grown increasingly disturbing over the last 48 hours, prompting us to notify the police," Mr Wills said.

"We were advised by the police to reach out to the makers of the original posts and ask them to take the posts down."

NSW Police were unable to confirm whether or not threats regarding the listing had been reported.

Questions around ethics and laws

Demi Swain, a senior associate at Bennett Litigation and Commercial Law, said it's not illegal to post someone's personal information online, "provided it's all public information", but it could be considered intimidation or harassment.

"There's various consequences if people are engaging in that type of behaviour. I think just obviously, rather than attacking in that manner, it's not strategically smart."

It's also not illegal to post a negative review.

Hugh Breakey, an ethicist at Griffith University added there's nothing unethical about posting negative opinions online, such as a Reddit thread.

"Precisely one of the reasons we have freedom of speech is so people can talk and think about things that are going on that they have ethical worries about."

But Dr Breakey said when something does err towards the side social punishment, like review bombing or sharing personal information online, it becomes ethically more complicated.

On one level, this type of internet vigilantism can informed by misinformation and escalate quickly. 

"The ethics of social punishment is itself pretty murky, because it's pretty easy to get this stuff wrong," he said.

But it can also be considered a form of punitive action. 

"You're trying to call out someone, and you're attaching their name and sort of identifiable information to what they are doing," Dr Breakey said on publishing personal information.

"And that's a confronting thing to do in any context."

'You can't control how significant that information winds up being'

Another concern around sharing personal information online is, once it's amplified, the situation may have unintended consequences.

"The general point is that, one of the reasons to be wary about this, is because you can't control how significant that information winds up being," Dr Breakey said.

In October 2023, a number of university students in the US were vilified when an open letter they signed in support of Palestine following October 7 was posted on social media. 

Those students later experienced doxxing, stalking and assault.

"These types of social punishment — and I think this is a type of social punishment — is probably a lot more ethically problematic than it feels to the person in the moment when they are doing it."

In his email to the ABC, Mr Wills said Wills Property regrets "that this matter has been allowed to blow out of all proportion".

For Cords9836, while they empathise with the agency being harassed, they said it doesn't justify their behaviour.

"But I don't think how they've responded to the situation was okay, either."