The developer of controversial Facebook app Fan Check claims the software carries no viruses and is safe and legitimate, despite rumours on the web.

The app has been making waves on Twitter, blogs and message boards as users claim it will install malicious software on your PC.

However, Janakan Arulkumarasan claims the rumours have been started by hackers in the hope that unspecting web users will search for information about the app and navigate to pages loaded with fake anti-virus software that steals personal data.

"FanCheck is NOT a malicious app. Unfortunately, some malicious developers have been spreading a lie that it is - and encouraging people to download fake virus scanning software, which damages their computer. This is very unfortunate, but it has nothing to do with us," said Arulkumarasan, who describes himself as a Hong Kong-based entrepreneur.

Security firm Sophos has backed-up his claim that hackers are captialising on the web discussions about the app.

Arulkumarasan launched the application in late July, initially calling it StalkerCheck, a name Facebook asked him to change.

Since then, it has become very popular, although the popularity seems to be waning, maybe due to the controversy surrounding it. Many Facebook members have left messages in the application's page complaining that FanCheck disrupted their Facebook profiles and their PCs as well.

The developer challenges these accusations.

"In general, applications can never damage your profile or PC unless they ask you to install something on your computer. FanCheck does not, and never has asked people to install anything on their computer, although it did require Adobe Flash to work," Arulkumarasan said.

Some of the initial interest in the application may have stemmed from the incorrect belief that FanCheck would allow people to create logs of who visited their Facebook profile and what they viewed there.

In fact, Facebook makes it impossible for applications and users to gather this type of passive-browsing information. Facebook members can't know who has silently viewed their pages, photos, videos and other content they have posted.

The misperception that FanCheck could uncover this type of data led Facebook to ask Arulkumarasan to make the application's description clearer, Facebook said.

According to Arulkumarasan, FanCheck calculates who are your biggest Facebook fans - previously 'stalkers' - by counting the number of times they interact with your profile, by writing on your wall, posting comments, 'liking' posts and so on.

"[It] then ranks friends in order of how often they interact with your profile. It does NOT measure page views, photo views or anything which doesn't involve a wall post - so simply viewing someone's profile won't get you on the list," Arulkumarasan said.

"Facebook has never asked me to take the application down," Arulkumarasan said.

He also defended the notifications generated from the application and said they comply with Facebook's guidelines.

FanCheck users can tag friends in their ‘fan' list, so that a thumbnail image of the screenshot gets posted to their tagged friends' profiles along with a link inviting them to install the application. A thumbnail image is also broadcast to the friends of those tagged friends.

At first glance, this seems like the type of spammy and confusing application-notification method that Facebook has tried to eradicate. Not so, said Arulkumarasan.

"When I first launched the application, a large number of users started taking screenshots of their fan list, and manually tagging their friends. A lot of users don't know how to do this on their computers, so a few days ago, I decided to make it an optional, one-click button," he said.

"We never forced users to share and tag photos, and we never did anything without their permission. We simply made it easier to do something that users were already doing."

"I should also note that tagging photos using applications is NOT against Facebook terms," he added.

Facebook said it has reviewed the application and hasn't found it to contain malware, although it revealed it hasn't completed a full  investigation on the way the application sends notifications to users because that functionality was added shortly before the developer took down the application.

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