It is marketed as the perfect solution for worried mothers and vigilant bosses: secret mobile phone spyware that monitors a person's texts, calls, photos, emails and web browsing.
''I can now keep an eye on my babies - even when I'm at work!'' reads a testimonial for one spyware product.
''Now that we know the truth, our profits are up by more than 10%!'' another happy customer reports.
Yet new technologies such as GPS trackers and mobile phone spyware are increasingly being used to stalk, harass and threaten women in a new form of domestic abuse that legal experts say is highly disturbing.
MobiStealth, the product that received such rave reviews online, was used by convicted murderer Simon Gittany to read his girlfriend Lisa Harnum's text messages, one of several forms of control and surveillance he subjected her to.
The product's website encourages potential buyers to ''get the answers you deserve''.
When Gittany learned of Ms Harnum's plan to escape the abusive relationship in July 2011, he threw her off the balcony of their 15th-floor Sydney apartment.
In a Victorian study last year, 97 per cent of domestic violence workers reported that perpetrators were using mobile technologies to monitor and harass women in domestic situations.
Two-thirds of the 46 victims interviewed said they were made to feel like they were being watched or tracked, yet less than half told somebody about it.
One victim's partner was monitoring her emails after hacking her account and another had her Facebook page saturated with graphic information by a former partner. One woman was tracked to a refuge using a GPS-based smartphone application.
''Technology has facilitated invasions of privacy that would have been unimaginable 10 years ago,'' the Women's Legal Service wrote in a submission to the Australian Law Reform Commission's inquiry into privacy laws in the digital era.
The group said laws to deal with the abuse of new technologies were ''unclear and inadequate'' and it called for stronger legislation. The commission will hand its final report to the Attorney-General by June.
Mobile phone spyware costs as little as $6 a month and needs to be installed physically on a phone once for it to operate without the owner's knowledge.
Shane Johnson, a spokesman for Sydney company Spousebusters, said it sold ''hundreds'' of GPS trackers, hidden cameras, listening bugs and spyware programs a year. The company asks no questions of purchasers and takes no responsibility for people using legal products to commit illegal acts.
Domestic violence researcher Delanie Woodlock said digital harassment had become easier and it resulted in the same detrimental psychological impact as physical abuse.
''It's easier to create this sense of omnipresence, the feeling that a partner has total control,'' she said.
A NSW Police spokesman said there was a ''fairly robust legal regime" to protect personal privacy and prohibit the abuse of technology. This included offences of stalking and intimidation and legislation covering hacking, spying and accessing data without consent.