As pressure mounts on firms such as Google, Facebook and Twitter to do more to tackle fake news, some are taking things into their own hands.
Technologist Daniel Sieradski has developed a plug-in – known as BS Detector – that flags up “questionable” websites on Facebook and Twitter.
The plug-in – has appeared in dozens of news feeds, leading some to think it was an official Facebook feature.
It appears Facebook is currently blocking links to the site.
BS Detector is a plug-in that uses a list of fake news sources as its reference point. It can be added to Chrome and Mozilla browsers and when it spots a potentially false story, flags it with a red banner reading: “This website is considered a questionable source.”
It was created, Mr Sieradski said, “in about an hour” as a “rejoinder to Mark Zuckerberg’s dubious claims that Facebook is unable to substantively address the proliferation of fake news on its platform”.
It has had over 25,000 installs since launch. “I and other open source contributors have spent many more hours improving its functionality,” Mr Sieradski told the BBC.
Since that article was published, Facebook appears to have blocked anyone from posting a link to the BS Detector website.
“Facebook now provides a security warning and disallows you to do so,” Mr Sieradski told the BBC.
Facebook said that it was “looking into the matter”.