The arrival of hundreds of thousands of migrants and refugees in Europe over the past year brought with it many legitimate concerns – but also plenty of illegitimate ones, too.

Misinformation and rumors that painted refugees as criminals or worse have spread widely online. In some cases it was silly – a viral image of a supposed recent refugee holding an Islamic State flag that showed neither a recent refugee nor an Islamic State flag – but in other cases it was surprisingly important. One high-profile case involving rape allegations against a group of refugee men sparked a war of words between Russia and Germany, despite the fact it was soon dismissed as fabricated.

In a bid to filter fiction from fact, Karolin Schwarz and Lutz Helm decided to set up a website to counter and quantify these "hoaxes." The result, dubbed "Hoaxmap," marks each fake story on a map. Clicking on the story reveals the details of the hoax, as well as a link to a full story about the incident that reveals how it is wrong.

Schwarz told WorldViews she first began to notice these rumors taking hold last summer, when the surge in numbers of refugees reaching Europe first reached headlines. After the number of rumors seemed to surge in January, she worked with her friend Helm to set up a map "so people can check for their locations and if the stories they're hearing have been debunked."

For example, one remarkable rumor from the town of Bautzen suggested that local refugees had been urinating on the shelves of the local supermarket. Hoaxmap lists this claim but then links to an interview Suddeutsche Zeitung did with Gorlitz district police chief Conny Stiehl. "I have sent our people in every supermarket to ask," Stiehl said. "Not a single case has been confirmed."

Readers can send in their own additions to the map. So far, Hoaxmap claims to have identified 241 items, most of which are in Germany, with some in Switzerland and Austria. Schwarz says they noticed some patterns. "There are a lot of stories referring to false accusations of theft or rape," she says. "One recurring story is about supermarkets having to close shop because of too many refugees stealing there."

The hope is that Hoaxmap can soon expand with the aid of translations (at present, everything on the website is in German). Within Germany, the reaction has been pretty positive: Justice Minister Heiko Maas praised the map on Twitter, dubbing it "facts instead of prejudice."

Schwarz says there has been a backlash to Hoaxmap, but it only confirmed her view of who was behind much of the misinformation. "Since far-right groups are involved in spreading these rumors, we had to expect that they wouldn't thank us for creating the map," she said.

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