Earlier this week, however, BuzzFeed reported that fake stories generated more engagement on Facebook in the last three months of the election than stories from reputable news sources. The top 20 stories on fake sites generated 8,711,000 shares, reactions, and comments on Facebook; the top 20 stories from 19 major news outlets had 7,367,000, the site found.

Weeding out those hoaxes was the focus of a hackathon at Princeton University this week, where students built an algorithm that authenticates what is real and what is fake on Facebook. It takes into account factors such as the source’s credibility and cross-checks the content with other news stories before placing a “verified” or “not verified” label on each post.

The Washington Post notes that the students’ algorithm received intense interest this week, overwhelming their servers and causing them to take it offline. It is available on GitHub and as a Chrome Web extension.