It's currently available as a plug-in on Chrome and Microsoft's Edge mobile browser. Go to a site it has concerns about and a warning will be issued.
NewsGuard is planning, and staffing up for, an April launch in the UK but has already rated the Daily Mail's sister online publication, Mail Online.
To be blunt, this wasn't very good news. Anyone using the plug-in would have received a warning note, in red, which states the site does not maintain a basic level of accuracy and accountability.
As one might imagine, Mail Online tells Press Gazette that it is outraged and needs the rating to be corrected. NewsGuard tells the site that they tried calling and emailing Mail Online to discuss its rating but with little success.
It is interesting not only because it shows how an accuracy rater beyond the UK thinks of one of our most successful news sites, but also because of what could happen next.
Many UK newspapers are currently being examined by the NewsGuard team, including The Sun, The Guardian, The Times and The Telegraph, among others.
The NewsGuard system scores a news site on nine criteria and it claims that Mail Online came up short on six. Specifically, the site was found wanting when it came to avoiding deceptive headlines and managing the difference between opinion and news.
Let's face it -- I think most media observers in the UK would say the start-up has a point there. All too often, opinion and news is blurred by the Daily Mail, and hence Mail Online. They don't need repeating, but the front page usually features a sensationalist, eye-grabbing headline, which complains about immigrants and Brexit or law and order with a fair bit of comment about people on benefits in there too.
For the people it is aimed at -- basically the old and grumpy who want to say "you see, it isn't just me" -- the paper is hugely successful. However, if you were going to judge it for its headlines and its ability to separate commentary and opinion from news reporting, most people would probably find it comes up short.
While its execs grapple with this poor rating from NewsGuard, it is hard to imagine this is the end of the issue as other British newspapers come under inspection. It is a bad time for them to be judged ,because Brexit has seen papers deviate from the BBC approach of fair and impartial reporting as they pick sides and take pot shots at those who disagree with them.
Trust me -- this is just the beginning of this story. The country's "red top" tabloids have yet to be graded, and while The Times is likely to pass with flying colours, I suspect The Telegraph and its hard Brexit supporting columnists and the resulting headlines, will warrant a closer inspection before it is believed to have passed the test of separating opinion and news.
It is unlikely that Mail Online is the only UK news source to be questioning its status with this Chrome and Edge plug-in by the time it launches in April. UK journalism is caught in the grip of a furious Brexit debate and may struggle to show that it is beyond reproach.